New message added informing how to exit fullscreen mode.

Fixing this bug in the full screen mode involves patching it
on noVNC codebase.
This patch adds a comment for how to exit the full screen
mode using the browser's back button.

Change-Id: Ibcf510efadd6a1f29e0b2693ce9e332d54652d62
Closes-Bug:1251196
Remove unused arg `instances`

In function VolumeTableMixIn._set_id_if_nameless(), we
define arg `instances`, but we never use it.

Closes-Bug: #1269200

Change-Id: Iac828511bfe8cd417a9c965d063c388fde73052e
Remove Create Backup Action For Non-Active

the "create backup" action is incorrectly shown for a non-active
database instance in the database instances table. now, only if the
instance is active, will the action/button appear.

in addition, non-active instances are now excluded from the dropdown
in the create-backup workflow.

Change-Id: Id9fdeab84ad91b96ba1a9f07ee6d1af87b6320f7
Closes-Bug: #1268260
Merge "Remove unused arg `instances`"
Merge "New message added informing how to exit fullscreen mode."
Merge "Remove Create Backup Action For Non-Active"