[BUGFIX] Adds Solr re-index after tagging as outdated

* Touches the extension's timestamp for indexer

Change-Id: I59edd6e2bb34d6044adb012b688a7aaa35b648ae
Resolves: #54383
Reviewed-on: http://review.typo3.org/31499
Reviewed-by: Christian Zenker <typo3@xopn.de>
Tested-by: Christian Zenker <typo3@xopn.de>