Fix issue #115: WellFormednessChecker should check for null in ids.

Added a check for null record ids to the WellFormednessChecker.
Added tests for WellformednessChecker.
Unified capitalisation of WellformednessChecker.
Fixes for modules and tests that used null as record id.
Merge pull request #116 from cboehme/issue-115-null-record-ids

Improvements for the WellformednessChecker