monster insertion of Apache license headers

This is a crazy PR, let me explain it:

I added a python script: ```find-missing-apache-headers.py```
https://github.com/jrenner/libgdx/blob/insert-apache-header/find-apache.py
 in the base libgdx directory (don't know where else to put it).  This script will find any source files (currently only .java, but configurable) that are missing the Apache header under the libgdx dir tree.  It then gives you the option to insert the header.  This PR is the result of running that script. I was able to do the ant build sucessfully after running the script.

Things I don't know about:
* Do all these files need the header?  I don't know about box2d, bullet, other third party stuff.
* Does anyone really care about this?
* What other source extensions does this need to work for?

All in all I think I just wanted to write some python.  My feelings won't be hurt at all if this gets closed without a merge.