Whether the fluid is saturated or not is explicitly passed to the pvts

The criteria for whether the fluid is saturated or not is moved from the
within the pvt calculations to the solver, and passed to the pvt
calculations as a array of Boolean values.

The new criteria is set to Sg>0. (From rs >= rsBbp).  With this criteria the convergences problems 
is gone for the SPE9 simple case and moreover the overall number of iterations is reduced.  

This update depends on OPM/opm-core#434