There were two middlewares using a common pattern to load
the proxy-server app config section. The existing pattern
fails to recognise option overrides that are declared using
paste-deploy's 'set' notation, as illustrated by the change
to test_dlo.py in this patch.
This patch replaces the existing code with a helper function
that loads the proxy-server config using the paste-deploy loader.
The resulting config dict is therefore exactly the same as that
used to initialise the proxy-server app.
Change-Id: Ib58ce03e2010f41e7eb11f1a6dc78b0b7f55d466
dd113ab25a