Changes at csv and xls ui

Invalid states of pages do no longer keep previous load information.
Fixed error messages (there should no longer neutralize each other).
Fixed some setPageComplete issues.

Add "select Type" functionallity to csv and xls instance exporter.
Notice: All types are shown, but only types with at least one instance can
be selected.

Export Writer now support selected Type
Fixed an issue with blank cells at the end of each row. (So headerlength
is not equal to row length)

Change-Id: Id861132713ae3533a3baec73dca4579538ee81e2
Reviewed-on: http://gerrit.esdi-community.eu/3167
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>