remove the need for cl

The `return' function is not supported by emacs by default.  This
causes the following error when `bundle-open' is run from outside a
gem / Rails source tree where a Gemfile can't be found:

return-from: No catch for tag: --cl-block-nil--, nil
handle superfluous 'Removing dependencies...' message from bundler

bundler really should have output this on STDERR not STDOUT, but
we need to handle it anyway.