Allow `order_by` and `sort` parameters to `/api/v3/groups.json`. At
present, only ordering by name and path is supported, and the default
sort is name ascending (alphabetical order).

Fix invalid JSON in Builds API doc

See merge request !7475

Issue #4270: Recursive option for files through API

## What does this MR do?
- Adds recursive param to tree API request. With this param we can get all repository paths in a single request. 
- Related [old github pull request](https://github.com/gitlabhq/gitlabhq/pull/9311)

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

## Why was this MR needed?
Requested in #4270 
## Screenshots (if relevant)

## 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
  - [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)

## What are the relevant issue numbers?
Requested in #4270

See merge request !6088

Add button to delete all merged branches

## What does this MR do?

It adds a button to the branches page that the user can use to delete all the branches that are already merged. This can be used to clean up all the branches that were forgotten to delete while merging MRs.

**Note**  
~~This MR is WIP until MR !6408 is merged.~~

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

The UX of the actual "Delete merged branches" button.

## Why was this MR needed?

Fixes #21076

## Screenshots
![Branches page without "Delete all merged" button](/uploads/3a2936a83c3547a0fce92a74af880a2d/Screen_Shot_2016-10-17_at_20.06.30.png)

Before:
![Screen_Shot_2016-10-17_at_20.07.11](/uploads/55efcebf4e0a45dbfc70ba4a11ca152c/Screen_Shot_2016-10-17_at_20.07.11.png)


After:

## 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
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [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)

## What are the relevant issue numbers?

Closes #21076

See merge request !6449

The JSON of the example responses were missing a few `,` and therefor
invalid. This adds them to make those JSONs valid.

Add api endpoint `/groups/owned`

See merge request !7103

It adds a button to the branches page that the user can use to delete
all the branches that are already merged. This can be used to clean up
all the branches that were forgotten to delete while merging MRs.

Fixes #21076.

Add query param to filter users by 'external' & 'blocked' type on API

Closes #23731

See merge request !7109