Return the master services plugins

def engines(opts, functions, runners, utils, proxy=None):
    '''
    Return the master services plugins
    '''
    pack = {'__salt__': functions,
            '__runners__': runners,
            '__proxy__': proxy,
            '__utils__': utils}
    return LazyLoader(
        _module_dirs(opts, 'engines'),
        opts,
        tag='engines',
        pack=pack,
    )