android library xml files generated by gradle

I'm not sure if this should be added to the .gitignore or just merged in. This link says that it could go either way, but since there are already other library xml files in the repo I included mine. It's up to you @twuster.

 https://intellij-support.jetbrains.com/entries/23393067-How-to-manage-projects-under-Version-Control-Systems