Creates new remotes if needed and fetches objects before cherry-picking.

    $ git cherry-pick http://github.com/mislav/REPO/commit/SHA
    > git remote add -f mislav git://github.com/mislav/REPO.git
    > git cherry-pick SHA

A remote must be an existing repo on GitHub.

    $ git fetch mislav
    > git remote add mislav git://github.com/mislav/REPO.git
    > git fetch mislav

If users keep the gem installed, they have a chance to be notified of updates
and they can refresh their standalone script. Also, executables in ~/bin should
have precedence over gem executables, so no need to uninstall.

New abilities:

  $ hub compare
  -> When on a branch that tracks "remotebranch", for example,
     this opens "github.com/user/repo/compare/remotebranch".
     In effect if the tracked branch is not "master".

  $ hub browse reque issues
  -> open http://github.com/user/resque/issues

  $ hub browse
  -> When on a branch that tracks "remotebranch", for example,
     this opens "github.com/user/repo/tree/remotebranch".
     In effect if the tracked branch is not "master".

  $ hub browse -- commits
  -> open http://github.com/user/repo/commits/master

  If this branch is tracking a remote branch:
  -> open http://github.com/user/repo/commits/remotebranch

Supported subpages:

  - "tree" (default)
  - "wiki"
  - "commits"
  - "issues", "network", "downloads" or any other arbitrary
    string is simply appended to URL path

Fixed a problem in the ronn file this caused.

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