TIKA-1171 -- extra asterisks from master slide in PPT; added tests to TIKA-712 test files to show 1171 was fixed.  Borrowed extraction code from POI PowerPointExtractor

git-svn-id: https://svn.apache.org/repos/asf/tika/trunk@1527030 13f79535-47bb-0310-9956-ffa450edef68