Usage example:

  $ git fork
  (forks "defunkt/hub" on GitHub)
  (git remote add mislav git@github.com:mislav/hub.git)
  new remote: mislav

Use `git fork --no-remote` to skip adding the new remote.

Tests use Webmock for stubbing out HTTP requests:

  $ gem install webmock

useful for jumping to the GitHub page of the repo checked out in the current directory

most of the time it's `git`, but in some cases it can be a different
executable like `open` for `hub browse` or `echo` in testing