Catch InstanceIsLocked exception on server actions

If the server is locked, server actions raise 409 error, and the error
message is like "Instance is in an invalid state for 'pause(action name)'". The
error message is inappropriate, two points:
1. the state is valid for pause
2. the message doesn't tell that the instance is locked

The patch fixes the problem, and will modify on v2 and v3.

Change-Id: I7e21037b9abca5a3fd0f64dd5621e88dcf1a3c21
Closes-Bug: #1256873
Merge "Catch InstanceIsLocked exception on server actions"