Ditch JOhm and switch to YAML flatfile persistence.

Redis, while it certainly has its flair, does not significantly benifit Demigods enough to warrant a required install for each Demigods server.  YAML, being already the standard for many Minecraft plugins, if it can match the same speed and accuracy that JOhm and Redis provided, should be accepted as the new persistence method.

Steps before merge:
- [x] Finish porting everything.
- [x] Fix data mysteriously disappearing.
- [x] Fix data becoming corrupt because of concurrent modification (null errors, null errors everywhere).
- [ ] Extensive performance testing.
- [x] Stop massive lag spikes when testing with more than 3 players.
- [ ] Enthusiastic celebration! Invite everybody minus EvilSeph (nobody likes him).