Updated tutorials to converge pressure during PIMPLE loop to avoid
phase-fraction unboundedness which limits thermodynamics convergence.

Reduces or eliminates staggering patterns due to cell-force imbalances
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1363

BUG: twoPhaseEulerFoam: removed multiple of the continuous phase fraction from force and heat transfer models

twoPhaseEulerFoam: Remove k from the Reynolds stress because there is only a single pressure in the system
and to avoid the generation of flow from the gradient of k the pressure gradient must balance the k term in
each U equation