adding "mappingCategory" to commonProps temporarily, quick fix for InfoPortalCommon

This (workaround) fix soley adds a "mappingCategory" property to the commonProps.

Following the conclusion of last fridays TF-DP meeting, this is a quick fix for the information Portal to be able to start using first "recordMetadata" properties, until we sort out how to include the full "recordMetadata" sub-schema dynamically and sustainably. See #49