Remove generic exception catching for admin_actions API v3

* Remove generic exception catching
* Add exceptions InstanceNotFound, InstanceIsLocked, FlavorNotFound,
CannotResizeToSameFlavor, TooManyInstances catching
* Add decorator extensions.expected_errors

Partially implements bp v3-api-extension-versioning

Change-Id: I4e1d15a080e904e83e930fe15060b60c488a2f1f
Merge "Remove generic exception catching for admin_actions API v3"