Change-Id: I1ed2983cf574ebd565eeac4f8199fbc3a2e29c8e

The current identity role list command (both v2 and v3) is
overloaded with listing roles as well as assignments (if you
provide user, group, project or domain options). This is in
addition to the v3 assignment list command designed for this
purpose.

This overloading complicates the fact that roles can now be
domain specific (i.e. have a domain attribute), so the
command 'role list --domain <domain-name' will soon become
ambigious (this is in a follow on patch).

This patch:

- Adds a v2 assignments list, with support for pulling the
user and project from the auth credentials
- For comapability, adds the same auth support to the
existing v3 assignments list
- Deprecates the use of role list and user role list to list
assignments

Change-Id: I65bafdef4f8c89e863dab101369d0d629fa818b8
Partial-Bug: 1605774

Some files have execute permission unnecessarily. Change them from
755 to 644.

Change-Id: I471ebd1c3d123ad4a7376f7f5996f53f8c2d9b0b

Usually we use "(s)" to show about multi deletion in
help message. In addition, I think "EC2 credentials"
is better than "EC2 keys" in the error message.

Change-Id: I6a6461291542701d87a55d9ea0ea1fda6db04601

When an exception was caught and rethrown,
it should call 'raise' without any arguments
because it shows the place where an exception
occured initially instead of place where the exception re-raised.

Change-Id: I5fb6dea5da7fb6e1e2b339a713c7d37f8c99e407

Commands are "ec2 credentials delete", "service delete", "endpoint delete".
Also update their unit tests and functional tests.

Partial-Bug: #1592906
Change-Id: I1a0b7160b803a523646d09d030e6f112c81c4c24

Change-Id: I5307f949b3a350e41840a4a5c191ceacf1b3b291
Partially-Implements: blueprint log-usage

Use file logger for all command specific logs.

This patch also fixes some usage that doesn't
follow rules in:
http://docs.openstack.org/developer/oslo.i18n/guidelines.html

After this patch, all self.log and self.app.log
will be standardized to LOG().

NOTE: In shell.py, we got the log in class OpenStackShell,
      which is also known as self.app.log in other classes.
      This logger is used to record non-command-specific logs.
      So we leave it as-is.

Change-Id: I114f73ee6c7e84593d71e724bc1ad00d343c1896
Implements: blueprint log-usage

Migrate 'change', 'update' to 'modify',
migrate 'user to delete' to 'user(s) to delete',
migrate '(name or ID)' to '(type, name or ID)'.

Change-Id: Ie425e178bb5ddf773e6e793fcd91c78e9c4a5053