Add 'instance-usage-audit-log' plugin for V2.1

This patch adds 'instance-usage-audit-log' plugin for V2.1 API.
Also implement the API sample tests and share the unit tests
between V2 & V2.1.

Partially implements blueprint v2-on-v3-api

Change-Id: I152d00fb4b12942515d5db54a7ec381279c31ccd
Compute: set instance to ERROR if resume fails

Commit 5974c441bd538897bd4547e6a05ee27216461d97 added support for
ensuring that an instance is moved to ERROR if suspend fails.
This does the same for resume.

Change-Id: I5b1be6ad0c7b59047d53d82f83f22be4d7cb7ab2
Merge "Add 'instance-usage-audit-log' plugin for V2.1"