Correction in quota_client's condition logic

Replacing ">=0" with "is not None" so that we will be able to test
things like setting cores == 0 (to effectively disable an account).

Change-Id: Iaf9e2ff3190faca92594055a134cc1822afae60e
Implements: blueprint correction-in-quotas-client
Remove unnecessary client alias in console tests

Change-Id: I264a688c996b38204d5206e1d613aa024cd2e6bf
Merge "Correction in quota_client's condition logic"
Merge "Remove unnecessary client alias in console tests"