Add support for the extra route extension in the NVP plugin.

The underlying feature is available in NVP 3.2, which introduces a
new type of router. Therefore, create_lrouter needs to be made
version 'aware'.

This led to a number of fixes in the nvplib, especially around how
version is retrieved and how version-dependent methods are called.

Implements blueprint nvp-extra-route-extension

Change-Id: Ie4e2d93f70e1948a62563c8523aea61bb2194c84
Modify the OVS agent to support multiple tunnel_types concurrently.

This change modifies the "tunnel_type" configuration option to be a ListOpt
instead of a StrOpt. This is intended to allow the agent to work in an ML2
environment where multiple, disparate "tunnel_types" are supported at the
same time. For now, the agent will enforce a single "tunnel_type".

Fixes bug #1191089

Change-Id: Ic025e54a8a3e92fe1fe44ebf08d71c2210c7d82b
Prevent possible server list damage in BigSwitch plugin

The old failover logic for the BigSwitch plugin modified a
list of controllers as it tested them. If the code for one
thread unexpectedly raised an exception or died, the global
server list could lose a server permanently.
This patch addresses that by flagging servers as failed instead
so the global server list is never modified.

Fixes: bug #1200022
Change-Id: Id2dcb820ef9f62fd03e3215bff3345e56c78afe2
Merge "Modify the OVS agent to support multiple tunnel_types concurrently."
Merge "Prevent possible server list damage in BigSwitch plugin"
Merge "Add support for the extra route extension in the NVP plugin."
Imported Translations from Transifex

Change-Id: I241d1c1217fcf32e2d02832db15a9c5ab5da4359
Fix random OverflowError exceptions in gate-neutron-python26 tests

These errors seem to be linked to the NEC plugin and http connections
not being stubbed out correctly. This patch ensures do_request is
stubbed out prior to the tests execution; this should be enough
to prevent timeouts from occurring again. Stubbing out the call has
no effect on the coverage of the agent scheduler tests for the NEC
plugin.

Fixes bug #1201478

Change-Id: Iee3cb3cb3137cedcf97c707ea7fde9114b7264b6
Merge "Fix random OverflowError exceptions in gate-neutron-python26 tests"