Add lock status into output of instance detail view

Currently we only support locking/unlocking an instance but we are not able
to query whether the instance is locked or not.
This proposal is to add the lock status to the detailed view of an instance.

blue print link:
https://blueprints.launchpad.net/nova/+spec/get-lock-status-of-instance

Change-Id: I5d6e42849a61e68fbbe05c92752fa6584505d5bf
Merge "Add lock status into output of instance detail view"