Merge "Use db model hook to filter external network"

diff --cc quantum/db/db_base_plugin_v2.py
Simple merge

diff --cc quantum/db/l3_db.py
Simple merge

diff --cc quantum/plugins/nec/nec_plugin.py
Simple merge

diff --cc quantum/plugins/nicira/nicira_nvp_plugin/QuantumPlugin.py
Simple merge

diff --cc quantum/plugins/openvswitch/ovs_quantum_plugin.py
Simple merge

diff --cc quantum/plugins/ryu/ryu_quantum_plugin.py
Simple merge

diff --cc quantum/tests/unit/test_l3_plugin.py
Simple merge