Automatically initialize PETSc in flcbdfWrappers

* Simplify Comm init so it takes no arguments
* Assume sys.argv is default argv to pass in to PETSc
* Remove PETSc database options
* Automatically initialize DAETK and Comm/PETSc in flcbdfWrappers
* Replace DAETK-Comm with a simple Python comm
* Add some basic tests to verify Comm
* Remove Comm.init() from a few places it is no longer explicitly needed
* Replace Py_PETSC_COMM_WORLD with PROTEUS_COMM_WORLD
Here is the man page for the function this is based on:
http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscSequentialPhaseBegin.html

We had  just been calling this with ng=1 by default. So existing code  is  going to be expected  to use comm.beginSequential() with no arguments.