Add decent gradle setup

This is to get rid of the copied mess in the gradle setup scripts.
* changes added to this PR:
  * Removed some unneeded or unused functionality or plugins, that were just copied while setting this up i think, like maven.
  * Changed the run directory so everything what is used for running minecraft (like the saves and config folder) to /run so it is not making a mess of your local dev environment.
  * fix the replacing stuff in the Reference class.

* Added:
  * the the gradle wrappers and basic files, so people can at least easily setup the project on their own without having to download the according forge files themselves or installing gradle on their path. This is also useful when you start working with a CI like jenkins of some sort.
  * Added the `mcmod.info` as it is easier to change with gradle the the normal `MetaData` in code.
  * Added the tasks for building a dev and sources jar.
  * Added curse integration althouthg this might seem a little early I added it anyway. The only thing you need to do to get it working is adding a `curse.properties` file and adding the `api_token` and `project_id` to that file. Note that this file will not get pushed to github so your `api_token` will stay secret.