Added checks for null and equal class to .equals()

Also switched a check for null in OreHelper#sameOre to prevent null ==
null => true
Fixed typo in SyncData
Merge pull request #189 from yueh/typos

Fixed typo in SyncData
Update CONTRIBUTING.md
Update CONTRIBUTING.md

Removed urls cause they were not parsed in ```sections
Update CONTRIBUTING.md

And for pastebin
Merge pull request #188 from yueh/cleanup-code

Added checks for null and equal class to .equals()