Improve generated javadoc and zipfile

Add a better copyright notice to the footer of javadoc (include the
magical &copy; symbol, and the current year 2013).

Add the user-visible bits of the iOS and GWT backends to the javadoc
construction.

Change the version number to "0.9.9-SNAPSHOT", as I believe this is
where libGDX is.
Merge pull request #245 from bitiotic/javadocgen

Improve generated javadoc and zipfile