Remove noscript and head blocks from HTML.  Plus new unit tests.

Added a couple more blocks that should be removed from HTML by the parser before indexing.  Also added more unit tests to cover existing behaviour as well as this new behaviour.

To test, try using Smart Search to index an article containing \<noscript\> and \<head\> blocks and make sure that any text between the start and end tags is not searchable.  You should set your editor to "none" because the editor might remove those tags anyway.