Added required as optional argument to get_bin_path(). It defaults to
false. Updated following modules to use required=True when calling
get_bin_path(): apt_repository, easy_install, group, pip,
supervisorctl, and user.
Also removed _find_supervisorctl() from supervisorctl module and updated
_is_running() to not need it.
* Migraed easy_install, pip, service, setup, and user.
* Updated fail_json message in apt_repository
* Fixed easy_install to not hardcode location of virtualenv in
/usr/local/bin/.
* Made handling of virtualenv more consistent between easy_install and
pip.
