This sets up the HTTPProxyToWSGI middleware in front of Panko. The
purpose of thise middleware is to set up the request URL correctly in
case there is a proxy (For instance, a loadbalancer such as HAProxy)
in front of Panko.
So, for instance, when TLS connections are being terminated in the
proxy, and one tries to get the versions from the / resource of
Aodh, one will notice that the protocol is incorrect; It will show
'http' instead of 'https'. So this middleware handles such cases.
Thus helping Keystone discovery work correctly.
The HTTPProxyToWSGI is off by default and needs to be enabled via a
configuration value.
Change-Id: Ifa9dad55cfedeb8b804d675d3d4856af6096b039
Closes-Bug: #1590608
90faa85ecc