Port Juju core to go

Goal for 12.10:

The Go version launches with basic EC2 support, and as a platform on which we can build the future of the Juju project, and of service orchestration in general.

This will include the core juju commands, but will not include:

 * all pyjuju providers
 * any jitsu commands

Additionally some non-feature critical commands may not be supported:

 * debug hooks
 * persistent tunnel support
 * debug log
 * etc.

There will be 5 releases in the run-up to 12.10:

 * 1.1: *Aug 3* -- User Agent can run relation hooks
 * 1.2: *Aug 17* -- User Agent can handle unit workflow
 * 1.3: *Aug 31* -- Simple charms work (Begin testing charms and filing bugs)
 * 1.4: *Sept 14* -- Subordinate Charms, Relations, etc work (Key charms tested and working)
 * 1.5: *Sept 28* -- Release Candidate

And 2.0 should be available on *October 3*.