automate zoltan partitioning and genPUMI stage

[cekees]

When we run with the PUMI workflow for existing domain/mesh types, we need to run an unmodified input file to generate the mesh and let PUMI build its own representation of the domain geometry. Then we need to run zsplit to partition it and run a different input file to run in adaptivity. I think it may be possible to remove the requirement for users to manually run the first two steps by adding a domain argument to the PUMIDomain class that connects it with the user-defined domain, then catch that in NumericalSolution to run the genPUMI and zsplit phases before proceeding to the rest of the PUMI adaption workflow.