NVP: Add LOG.exception to see why router was not created

Add missing LOG.exception so that it exposes what error occurred.

Change-Id: I9194795678a6be59eb1d2555dfa99ca7a035c418
Closes-bug: #1269152
Use an independent iptables lock per namespace

Since iptables is independent from namespace to namespace, it makes
sense to use an independent lock per namespace.  This improvement is
aimed at improving the parallel performance in the L3 agent.

Partially implements blueprint: neutron-tempest-parallel

Change-Id: I15e9c9da9a7c15981757a09bc744501722d62db2
Base ML2 bulk support on the loaded drivers

Changes the ML2 plugin bulk support flag to
be based on the bulk support of the underlying
drivers.

Closes-Bug: #1272490
Change-Id: I28281c9ecc1696b929c7e0125d02a37946948744
Merge "Base ML2 bulk support on the loaded drivers"
Merge "NVP: Add LOG.exception to see why router was not created"
Merge "Use an independent iptables lock per namespace"