Return a list of service that are enabled on boot

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_enabled

def get_enabled():
    '''
    Return a list of service that are enabled on boot

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_enabled
    '''
    prefix = '/etc/rc[S{0}].d/S'.format(_get_runlevel())
    ret = set()
    lines = glob.glob('{0}*'.format(prefix))
    for line in lines:
        ret.add(re.split(prefix + r'\d+', line)[1])
    return sorted(ret)