backport Quantum metadata support

fixes: DHC-476

Backports the Nova Grizzly Metadata services changes that support
overlapping networks.  This can be used by updating Nova api-paste.ini
file to:

[app:metaapp]
paste.app_factory = \
akanda.nova.folsom.metadata.handler:MetadataRequestHandler.factory
add unit test for Port Alias table
Merge pull request #61 from markmcclain/meta

backport Quantum metadata support
Configure tox to discover and run tests

DHC-765
* create a django application to run tests
* configure tox.ini to use django tests runner
* pep8 clean up

Change-Id: I925cea7084512f1aca141a788256774f3f72c596
Merge pull request #63 from rodis/feature/port-alias-tests

Configure tox to discover and run tests