Created SetBiome Command

Yes its messy, Yes there is most definitely room to improve but it does change the selected area's biome without problems :)
Added canSetBiome() Permission
Updated plugin.yml to include /setbiome
Updated plugin main to include setbiome command executor
Update SetBiomeCommand.java
Fixed and final commit for setbiome command
Merge pull request #57 from JoshMorgan/SetBiome

SetBiome Command PR
Reset mentor and student fields after /mentor complete.
Merge pull request #7 from EmilHernvall/master

Merge from EmilHernvall:master