Switch run-time import to using importutils.import_module

.. and enable the cyclic-import pylint check, now that this particular
import is invisible to pylint.

Change-Id: I9bfe7f77742b0db3ebead6a6767ade9b91e54c22
Imported Translations from Transifex

For more information about this automatic import see:
https://wiki.openstack.org/wiki/Translations/Infrastructure

Change-Id: Ia8c01192a4c572a18bdcf987c188febb0c0a42f7
Catch DBReferenceError exception during binding a router

In some cases (Concurrent API tests) router can be deleted
before it is bound to an agent by scheduler.
That may lead to traces on L3 agent side returned via RPC.
Need to handle this case in more graceful way.

Change-Id: Ic52c26ace7f32a615150bd6098b244ae0b98250c
Closes-Bug: #1385257
Merge "Imported Translations from Transifex"
Merge "Catch DBReferenceError exception during binding a router"
Merge "Switch run-time import to using importutils.import_module"