v0.15.0b1

Version: 0.15.0b1

- Features:
    * Add additional init_argument to register method #86
    * Add @method decorator and handling #109

- Improvements:
    * inspect.getargspec() is deprecated, use inspect.signature() or inspect.getfullargspec() #94

- Tasks:
    * Bugs/fix update failed travis ci build #93
    * should use github actions to run CI checks to replace travis-ci #134