mojo should provide commands to inspect the spec

[Nick Moffitt]

A user of mojo should be able to run things like `mojo workspace list` and `mojo phase render deploy` to display important information about the current mojo spec and runtime environment. This has value for the documentation, as it gives a new user chances to inspect state and confirm assumptions. We can tell users a few commands to see how the templates will be rendered, and instructions for checking to see if you have set up the project/workspace stuff correctly.

The pattern of `<command> <noun> <verb> [<etc...>]` seems to be the future for juju's CLI, and we should aim for parity with that. We will want to revisit some of the nouns we currently use for concepts within mojo, as there are some that may benefit from more descriptive metaphors.