Use juju bundles and other primitives via JAAS

Currently any production or staging juju model has a juju bundle that describes how it should be deployed, and possibly a set of automation scripts described via mojo, or in the future via terraform. These can be version controlled, changes reviewed and approved before being applied.

JAAS should support this kind of a workflow. It currently seems to support the use case of an individual user operating on a model in isolation, but not as part of a team's workflow.