Move network test_quotas to admin directory

Replace superclass base.BaseNetworkTest with base.BaseAdminNetworkTest
Remove duplicate annocation

Change-Id: I95d3175ed2b97724c6e49ab2dbe771e3dcf7a7d7
Merge "Move network test_quotas to admin directory"
Merge branch 'master' of https://github.com/openstack/tempest