[COM_COURSES] add power point show extension to files handler
[COM_COURSES] add power point show extension to files handler

zweidner/hubzero-cms,zweidner/hubzero-cms,zooley/hubzero-cms,zooley/hubzero-cms,anthonyfuentes/hubzero-cms,zweidner/hubzero-cms,anthonyfuentes/hubzero-cms,zooley/hubzero-cms,zweidner/hubzero-cms,anthonyfuentes/hubzero-cms,anthonyfuentes/hubzero-cms,zooley/hubzero-cms