Add method to tell if a repo is managed or not.
Add a decorator that can be used for possibly missing API calls.
Overwrite repo definitions with ones from the server.

Additionally:
  - Add a message to the repo file indicating it is auto-generated.
  - Wrap the calls to potentially non-existant APIs in the @attempt
    decorator.
  - Remove an incorrectly implemented __str__ method from the Repo
    class.
  - Remove a now unnecessary update method from the Repo class.
  - Merge in server overrides when the Repo object is generated.