[PLG_TAGS_CITATIONS] Fixed php error.
[PLG_TAGS_CITATIONS] Fixed php error.

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