Serve local mirror using apache

There are enough behavioral differences between http and file urls
for pypi mirrors that we should do the local mirror via apache. That
way we're testing what we care about - consumption of changes in the
mirror context - and not what we don't - how well pip deals with file
urls.

Change-Id: Icb16e8bbe77c03f224d06010eeb6bd0877b0d6ca
Merge "Serve local mirror using apache"