OInstance and blank cells

Changed OInstance to Instance. And changed the population of instances. If the cell was a blank cell
the xls instance reader ignored the property but did not continue to the
next.

Change-Id: I83c4b1bc87b6bd22050381e79523f4302751eeb6
Reviewed-on: http://gerrit.esdi-community.eu/3109
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>