Going forward with 0.5.2, holding off on 0.6

[Clint Byrum]

Since there has been no discussion on the format: 2 issues present in
trunk, I will go ahead and defer any work on a 0.6 release of juju.

0.5.2, however, will go forward. I have created a 0.5 release series,
a build recipe, and a PPA for those pacakges.

0.5.2 will be based off the 0.5.1 tag (r543) and have:

* All major bug fixes since 0.5.1
* OpenStack provider backport
* fixed setup.py version
* origin==PPA pointed at 0.5 series of packages.