HeaderDoc documentation

I have begun the work of adding HeaderDoc comments to the Volley source. So far I have done most of the classes except for the services. Not everything is coming out as it should, due largely to problems with the current version of HeaderDoc. I am told, however, that HeaderDoc 8 will address issues like nested classes and other things inside classes that currently aren't working.

The HeaderDoc-generated files can be found here:
http://volleyserver.sourceforge.net/source/