BUG: forces FO with execFlowFunctionObject (including porosity)

When porosity is requested:

--> FOAM Warning :

From function virtual void Foam::forces::calcForcesMoment()
in file forces/forces.C at line 1174
Porosity effects requested, but no porosity models found in the database

/home/alex2/prashant/QA/MD2014/AUTOMATED_TEST_LOOP/MD2014-09Dec/16_localForce_execFlowFunctionObjects/motorBike @Mattijs