Makeflow / Work Queue Environment Support

Makeflow now cleanly generates a list of environment variables for each job, which is passed through the batch job interface to each driver.  Condor/Cluster drivers export variables before submission, while Chirp/WQ pass the variables explicitly down the pipe to the job and then setenv at the execution site.  

Along the way, I cleaned up the batch job interface by consolidate submit() and submit_simple() (the former was entirely unused), simplifying support for the combined cluster systems, and dropping support for hadoop, which was rickety and unused.

Cleaned up docs to correspond.

Were these removed on accident?