webhooks: include old revision in MR update events

## What does this MR do?

Includes the old revision for an MR in webhooks.

## Are there points in the code the reviewer needs to double check?

The docs do not give an example `update` hook; should I add one?

## Why was this MR needed?

In order to keep web hook listeners stateless, it helps to include the previous revision of the MR in the hook so that it does not need to remember the last revision (which may also be wrong in case of missed or out-of-order events due to previous errors).

## What are the relevant issue numbers?

N/A

## Screenshots (if relevant)

N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5535

Line tooltip up with icon

## What does this MR do?
Lines up tooltip with CI icon

## What are the relevant issue numbers?
Closes #20294 

## Screenshots (if relevant)
![Screen_Shot_2016-07-26_at_2.25.22_PM](/uploads/45b6328bc5676b6645d1b7a58803cec4/Screen_Shot_2016-07-26_at_2.25.22_PM.png)


See merge request !5508

Fix search results for notes without commits

part of #20063   

![deleted_commit](/uploads/5d99b9aedaf4f728425d95f7a9734d98/deleted_commit.png)

See merge request !5571

Pipelines/Builds updates

## What does this MR do?
Adds branch/tag icons in admin view; increase min-width of builds tables

## What are the relevant issue numbers?
#20139

## Screenshots (if relevant)
Branch icons:    
![Screen_Shot_2016-07-27_at_1.29.57_PM](/uploads/2fceddfed5ed1a28d9b7d5e2427cba93/Screen_Shot_2016-07-27_at_1.29.57_PM.png)

Reduce `icon-container` width, before:
![Screen_Shot_2016-07-27_at_5.29.32_PM](/uploads/e3fe38edc262f6460572e20102ef9b6d/Screen_Shot_2016-07-27_at_5.29.32_PM.png)
Reduce `icon-container` width, after:
![Screen_Shot_2016-07-27_at_5.29.03_PM](/uploads/58b82e2c1491672c95dfe35911891891/Screen_Shot_2016-07-27_at_5.29.03_PM.png)

See merge request !5527

Fix attr reader to force the intended values for source and target shas

## What does this MR do?

When importing a pull request from GitHub, the old and new branches may no longer actually exist by those names, but we need to recreate the merge
request diff with the right source and target shas.  We use these `target_branch_sha` and `source_branch_sha` attributes to force  these to the intended values. But the reader methods were always looking up to the target/source branch head instead of check if these values was  previously set, this MR applies a memoization pattern to both of them.

## Are there points in the code the reviewer needs to double check?

This [commit](https://gitlab.com/gitlab-org/gitlab-ce/commit/6ce25e7b4caa9e94de74378729178c7060d640b2) introduced this bug in the importer.

## What are the relevant issue numbers?

gitlab-org/gitlab-ce#20385

## Does this MR meet the acceptance criteria?

- [X] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [X] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [X] ~~API support added~~
- Tests
  - [X] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

/cc @akitaonrails @DouweM 

See merge request !5573

Avoid line_code and position calculation on line partial for plain view

See merge request !5591

Sensible state specific default sort order for issues and merge requests

## What does this MR do?

It provides more sensible default sort order for issues and merge requests based on the following table:

    | type           | state  | default sort order |
    |----------------|--------|--------------------|
    | issues         | open   | last created       |
    | issues         | closed | last updated       |
    | issues         | all    | last created       |
    | merge requests | open   | last created       |
    | merge requests | merged | last updated       |
    | merge requests | closed | last updated       |
    | merge requests | all    | last created       |

## Are there points in the code the reviewer needs to double check?

All the bits where `id_desc` was changed to `created_desc`.
 
I hope it's okay, It makes more sense in my opinion.

## Why was this MR needed?

Prior to this MR the issues and merge request were sorted based on `id_desc` by default. 

This MR aims to make the interface more user-friendly by providing state specific sorting defaults most users would expect. 

## What are the relevant issue numbers?

See #15064 

See merge request !5453

Fix Importing labels and milestones associations - Import/Export

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19510 and https://gitlab.com/gitlab-org/gitlab-ce/issues/19447
- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5426