turbulenceModels::RAS: Corrected sign of "C3" dilatation term

Set default value of C3 to 0
Set C3 to -0.33 in the engineFoam/kivaTest tutorial.

Resolves bug-report https://bugs.openfoam.org/view.php?id=2496

tutorials/combustion/engineFoam/kivaTest/constant/turbulenceProperties

@@ -24,6 +24,11 @@ RAS
     turbulence      on;
 
     printCoeffs     on;
+
+    kEpsilonCoeffs
+    {
+        C3          -0.33;
+    }
 }