Add missing help messages for nova-manage command

Add help messages of agent and logs subcommand(nova-manage)

Change-Id: Ic9adea9de4eb5cbe3b6c611dac9e2fd549ff0610
Port multinic extension to v3 API Part 2

Ports the multinic extension and the corresponding unittests to
the v3 framework.

Partially implements blueprint nova-v3-api

Change-Id: I5688b66734daa05eb92501f16a8413a194c5fa30
Fix misc issues with os-multinic v3 API extension

Fixes action names for the extension to be consistent with other
extensions

Replaces WebDav UnprocessableEntity return code with BadRequest
when the client body is bad

Cleanup exception handling

Partially implements blueprint nova-v3-api

Change-Id: Ied433fe6cf93d6724201035120612036dec53283
Add "ExtendedVolumes" API extension

- adds an API extension to include list of attached volumes with instance info
- adds v3 api porting as well

DocImpact

Implements blueprint servers-add-volume-list
Change-Id: If58dc40b093c2f61c6ae6b82fcd8f0bf53be464a
Merge "Add missing help messages for nova-manage command"
Merge "Add "ExtendedVolumes" API extension"
Merge "Port multinic extension to v3 API Part 2"
Merge "Fix misc issues with os-multinic v3 API extension"