Rework personaloverview tasklistings 

The Tasklistings (`MyTask`, `MyIssuedTask`, `AllTasks` and `AllIssuedTasks`) query now all the globalindex, instead of mixing Globalindex and Plone catalog queries.  

* Cleanup
* AdminUnit builder Fixes
* Introduce a specific query class for the Task sql-representation (The query class should replace the ITaskQuery utility in the future).

@deiferni