Implemented Automatic Versioning in Build Script

1. Changed build.gradle so that it edits the version numbers in
mod_pocketDim.java and mcmod.info.
2. Changed mod_pocketDim to use a placeholder for its version number and
fixed an annotation that was wrong. It would cause our mod_pocketDim
instance to not initialize properly. I removed what seemed to be
workarounds that were hiding the problem.
3. Fixed space in TileEntityDimDoor.invalidate() and corrected a
non-static access to a static field in mod_pocketDim.
4. Changed mcmod.info so that it users placeholders for the mod version
and MC version values.

src/main/resources/mcmod.info

@@ -6,10 +6,10 @@
 "modid": "dimdoors",
 "name": "Dimensional Doors",
 "description": "Bend and twist reality itself, creating pocket dimensions, rifts, and much more",
-"version": "1.6.4-R2.2.4",
+"version": "$version",
 "credits": "Created by StevenRS11, Coded by StevenRS11 and SenseiKiwi, Logo and Testing by Jaitsu",
 "logoFile": "/dimdoors_logo.png",
-"mcversion": "",
+"mcversion": "$mcversion",
 "url": "http://www.minecraftforum.net/topic/1650007-147smpssplan-dimensional-doors-v110-physics-what-physics-updated-with-fancy-opengl/",
 "updateUrl": "",
 "authors": [ "StevenRS11", "SenseiKiwi" ],