Dmedia 13.02 "Copy increasing"

As there was more work than expected this month on our Dbase32 encoding and finalizing the V1 hashing protocol, we weren't able to turn on the copy-increasing behaviours. So the plan is to turn on both the copy-increasing and the copy-decreasing behaviours in 13.03 (which kinda makes more sense anyway as they are complimentary behaviours).

Note that as of 13.02, we are no longer making releases for Ubuntu 12.04 LTS (Precise) nor Ubuntu 12.10 (Quantal). We recommend most users skip the 13.02 and 13.03 releases, which are higher risk as we turn on the remaining Dmedia behaviours. Instead, upgrade to Ubuntu Raring after its stable release comes out in April (13.04).

For details on how the V0 => V1 migration will work, please see this post:

https://plus.google.com/u/0/114471118004229223857/posts/SyZVjzqBNmA

Changes include:

 * Fixed a critical issue in the confidence downgrading behaviour: if a FileStore was missing its corresponding dmedia/store doc in CouchDB, the files it contained would never be downgraded by the store atime; now when the dmedia/store doc is missing, all files are immediately downgraded

 * Dropped Python 3.2 support, now requiring Python 3.3 or newer; now using os.sync() instead of calling /bin/sync; extractor now uses new timeout kwarg with subprocess.check_call() and friends, preventing the extractor from hanging

 * Lots of prep work for the migration to Dbase32 encoding for document IDs and for the migration to the final, version one hashing protocol

 * Ported from UDisks to UDisks2, which we now use through Gio.VolumeMonitor rather than directly through DBus; currently the auto-format functionality isn't available (although it was disabled by default anyway)