Remote repository support & revised variable formatting

Each host now keeps a local copy of the repository and deploys from it.

Move to the {name} style Python string formatting. It's easier for
developers to grok.

Ref #3
Move release name generation into the release module, use ISO8601
Merge branch 'feature/remote-repository' into develop
Prepare for backup/restore

Update documentation to discuss how backup & restore works. Now to
implement the actual rollback code.

Ref #4
Use versioneer
Versioneer is too complicated for our needs. Revert to something simple
Require PyYAML

Fix #6
Merge branch 'master' of github.com:fatbox/garment

Conflicts:
	setup.py