Fix inconsistent behaviour exceeding quota limit

Added quota checks for security groups, networks and routers. If quotas are
exceeded then buttons to create are disabled and feedback is given to the
user.

Appropriate tests are also in place

Change-Id: Ie49db5397d87a0c9a583b64e5de34460144b5956
Closes-bug: 1278449
Merge "Fix inconsistent behaviour exceeding quota limit"