Migrate lang repo to be able to create a jar as a dependency for AE2

At the moment the version is static, it needs to be made fit for the corresponding build system

@FireBall1725 might want to edit it to his needs

Upon calling `gradle jar` (since you dont have any tests running, you dont need `build`) you get a jar with following folder structure

/META-INF/manifest.mf
/assets/appliedenergistics2/lang/*,lang

the flat folder structure is kept so that contributors dont have to mess with the folders, the corresponding restructuring is done by the script.
The whole intention is to move away from the submodule system and use the more flexible gradle system. For example you can do stuff like

`compile api:appeng-lang:rv2-*` 

or something along the line to use the latest when the cached one is outdated without us touching the main buildscript.