Added world property 'allowFlight' to disable flying per world.  Does not have an override permission yet.  Adds #440.
Added "/mv gamerule" and "/mv gamerules" for setting and listing game rules per world.  Fixes #987.
Woo, Travis.ci!
Added bats to animals for the time being.  Fixes #996
Merge branch 'master' of https://github.com/Multiverse/Multiverse-Core