[COM_STOREFRONT] Add a default  argument value as per communityhub.purdue.edu/support/ticket/106
[COM_STOREFRONT] Add a default  argument value as per communityhub.purdue.edu/support/ticket/106

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