Add high performance gunicorn based wsgi wrapper

Also add pymysql to requirements so fully evented mysql queries can
happen.
Change pymysql requirement to <0.6.2 so that we can use it with Python 2.6

RM5425
Fix tests related to upstream changes

Upstream neutron change on database API:

Sync db code from oslo-incubator
Change-Id: I0e1d86878d3eb924b01e04dced0f90b4e57757d8
RM6180

Deadlock fix and off-by-one error.

Fixing unit tests. One-by-one. By one.

Unit tests fixed.

Removed super cool log messages.
.gitignore cleanup for PBR
Fix Gunicorn server config

* cfg.StringOpt -> cfg.StrOpt
* also reference the config options from the correct section
RM6442

Supports sending all the subnets with the ports to reduce the calls from nova
to neutron.