Neutron network delete fails with brocade plugin

(Cherry picked from master + resolved conflicts)

Fixes bug: 1223747

Change-Id: I4a8235d4dcb0c14477835afafd0b5459ce6b01f6
Multiple Neutron operations using script fails on Brocade Plugin

Fixes bug: 1223754

Change-Id: I5c0f99d5261f6a3c1e86fc77536c1237cc7815b7
Merge "Neutron network delete fails with brocade plugin" into stable/grizzly
Merge branch 'stable/grizzly' of https://github.com/openstack/quantum into grizzly/stable