add new command 'barc', client for arcyd

To make the arcyd workflow easier, create a client application which
will be able to do things like:

  - safely clean up local branches that have been landed
  - validate review branches before pushing them
  - show the status of review branches
  - assist in creating review branches

Created an empty new project with stubs for a command-suite app,
smoketests, autodoc.

Test Plan: $ ./precommit.sh