no quota for allowed address pair

There is no quota for allowed address pair. User can create unlimited
allowed address pairs.  I add quota for allowed address pairs.

Change-Id: Ie672373f770a4f9fe70d87a779cabc731413711a
Closes-Bug: #1336207
(cherry picked from commit I2efb0c0f527f1fb22c4d4b07f6d280863f565648)

Conflicts:
	neutron/tests/unit/services/loadbalancer/test_agent_scheduler.py

Closes-rally-bug: DE707