Fixes a problem where changes files with spaces in their paths would end up appearing as deleted content in Review Board diffs.  Changed the Perforce output format to use the -ztag switch, and then modified the parsing code to pull out the full path including the space(s).

This was a change that I originally attached to the following issue http://code.google.com/p/reviewboard/issues/detail?id=840

Tested on Mac OS X with a changed file that has a space in it's full path.