parameter descriptions for Shapefile providers

Change-Id: Ib2c54b8471bec7019b518c71cf539635aaea1af2
Reviewed-on: http://gerrit.esdi-community.eu/3126
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>