Create a new extension to the proxy, which will allow networks to be
extended across clouds.
Additionally, provide lots of documentation for this new feature.
Create a tox environment for running the unit tests against the lower
bounds of the dependencies.
Create a lower-constraints.txt to be used to enforce the lower bounds
in those tests.
Add openstack-tox-lower-constraints job to the zuul configuration.
for more details.
Signed-off-by: Doug Hellmann <email@example.com>