Reuse module `exceptions` from Oslo

The exception module in oslo common code and in keystoneclient are similar.
In case of unification openstack clients, we should use modules from Oslo.

Changes of this patch:
- imported exceptions from common code instead of `apiclient.exception`
- added aliases for exceptions which was renamed
(reason: backwards compatibility)
- moved exceptions `EmptyCatalog` from `apiclient.exception` to `exceptions`
- cleaned `apiclient.exception` from duplicated exceptions
- `apiclient.__init__` and `apiclient.exceptions` are kept and labeled as
'deprecated'(reason: backwards compatibility)

bp common-client-library-2

Change-Id: Iedf4e5d753d4278d81751ba0f55fdef3566b56de
Merge "Reuse module `exceptions` from Oslo"