New POI-general converter, for things other than excel, and convert the PDF converter too.
The POI-excel converter now does CSV properly, and notes exist for the Text mining converter on the Tika bits needed before it can be replaced.
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@20780 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
