Basic version for Android

No longer working, don't know why
With .gitignore to avoid bin/ folder
Readme file updated and converted to Markdown.
Balls can be added manually
Merge branch 'android' of https://github.com/pmudry/gdx2d into android
Added Android demo application. Not working in this commit.
Added .gitignore

To remove the generated output files in Android
Merge branch 'master' into android

Conflicts:
	gdx2d-desktop/src/hevs/gdx2d/demos/physics/collisions/BumpyBall.java
	gdx2d-desktop/src/hevs/gdx2d/demos/physics/collisions/DemoCollisionListener.java
Merge pull request #16 from pmudry/android

Android branch merged