I made 2 changes,
1. The initial viscosity value was 1e12, instead of 1e9 cm/s2(this value
is in Steve's notes. SO I changed that in diskSimulation

2. In MassMover, moveMass method had a negative Mdot difference so I
reversed the signs.

So now we do have surface density values that make sense when we run
simulation.
Now the second graph evolves fine, the surface density values are a bit
to high though. But later graphs give crazy values. I think the density
grid doesn't set the density values right