Move from Python logging to Openstack logging

Replacing usage of python standard logging module
with Openstack common logging module. Apart from
the said replacements, this patch also removes
basicConfig() setup from a couple of modules since
its not needed. Also removes unused LOG & imports.

Change-Id: I6a391951e00fb63905b2027270af9f401841d5b9
Closes-Bug: #1350937
Merge "Move from Python logging to Openstack logging"
DeferredBridge to allow add_tunnel_port passthru

The DeferredBridge should allow add_tunnel_port
method as passthrough in addition to add_port
and delete_port. L2Pop uses add_tunnel_port to
dynamically establish tunnel endpoints on cloud
nodes.

Closes-Bug: #1353885

Change-Id: I2e6d82ee79814e500604f4951e7d89eab662047a