Ported everything into android-studio

It was a mistake to do it with a feature branch, but now it's like it is - I
will now throw away 2 days of tears and sweat just to have a nice and clean
history...

Anyway, this commit adds everything (AnJaRoot, AnJaRootLibrary, AnJaRootTester
and AnJaRootDonate) into one android-studio project.
Update .gitignore and reduce Donate.apk in size

Updated app/.gitignore to include all the files which are created by ndk-build.
Also reduced Donate.apk in size by removing unused dependencies from build.