Update to 1.7.2 and migrate to Gradle

Still not ready but the bulk of update is finished. Big thanks to AbrarSyed for helping us migrate to Gradle and rest of Forge team for
allowing us to use their tools.

MCPC dev environment has been completely redone from scratch thanks to
AbrarSyed. The environment is setup identical to forge with Clean
being Forge/FML. The general process goes like this :

1. FML patches Vanilla
2. Forge patches FML
3. MCPC patches Forge
4. Distribution jars are built

We still have some work to do but 1.7 should be ready soon!
Fixed libraries not downloading from installer. Removed duplicate resources.
Added 1.7.2 mappings. Fixed TE canUpdate check. Fixed some login patches.
Update bukkit submodule
Updated some patches.
Fixed player login stalling.
Fixed some more patches.
Added missing spigot patch to fix chunks not loading after login.
Removed spigot antixray patches as we no longer use it.

Added some more missing MCPC patches.
Fixed plugins. Minor cleanup.
Updated SpecialSource to 1.7-SNAPSHOT
Fixed bukkit submodule.
Added new block place logic from 1.6.4 branch.
Updated README
Bunch more fixes. Lots of cleanup.
Added most of the remaining MCPC+ patches from 1.6.
Added PotionEffectType patch from 1.6.
Update to 1.7.2. Merge branch 'v172'