Add Storage Policy Support to Recon Middleware

Recon middleware returns object ring file MD5 sums; this patch
updates it to include other object files that may be present
because of Storage Policies.  Also adds unit test coverage for
the MD5 reporting function which previously had none.

The recon script will now check all rings the server responds with
match the on-disk md5's regardless of server-type; including any
storage policy object rings.

Note the small change to the ring save method, needed to
stimulate the right code paths in 2.6 and 2.7 versions of
gzip to enable testing of ring MD5 sums.

Change-Id: I01efd2999d6d9c57ee8693ac3a6236ace17c5566
Implements: blueprint storage-policies
Merge "Add Storage Policy Support to Recon Middleware" into feature/ec