--------------------------
* Improvements
* Refactor (323, 332, 367)
* Make juba.*keeper to allow 30 seconds or over as timeout time (330)
* New jenerator (373)
* Add CONTRIBUTING.md (376, 387)
* 188, 322, 333, 354, 390
* Bugfix
* Fix jubavisor to detect child process' exec failure (215, 362)
* Eliminate deadlock (329, 331, 375)
* Fix jubactl's save and load (342, 383, 384)
* Fix jubactl's segfault when using -N option (363, 388)
* 315, 319, 320, 327, 348, 358, 381, 385, 386