Set HTTPProxyTOWSGI middleware in front of congress.
Set HTTPProxyTOWSGI middleware in front of congress.

The purpose of this middleware is to set up the request URL correctly in
case there is a proxy in front of congress.

The HTTPProxyToWSGI is off by default and needs to be enabled via a
configuration value.

Change-Id: Ib0aaebbd42daa94e93ba1daefd3e84241f95e92a

ramineni/my_congress,ramineni/my_congress,openstack/congress,ramineni/my_congress,openstack/congress,ramineni/my_congress