Add postprocessor viscous_dissipation_statistics
Added test and changed output for time_in_years
Included the pressure in the calculation for cases that are not completely incompressible
Removed lines that were commented out
Added divergence of velocity
Remove /m from unit
Efficient calculation of divergence of velocity
Merge pull request #55 from anne-glerum/postprocessors

Postprocessor that calculates the viscous dissipation