Performance testing of asset metadata in course import/export

First iteration of code which tests performance of asset metadata during course import/export. Uses external code_block_timer module. Also, add script which validates XML file against an XSD file.
Agreed. My original intent was to make an object for this random data generation. Then I started changing methods over to static - and I never re-evaluated once they *all* became static. I'll get rid of the class.