Added tests for PipingCalculationException constructors. Added tests for PipingFailureMechanism as observerable. Removed non functioning tests in PipingDataTest regarding notifying when Output changed. Related to Issue [WTI-18] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@258 5a3db67b-de53-47b5-99c8-a1c30a6650e2