Implemented environment variable propagation in makeflow,
batch_job, and work_queue.  Drivers for chirp, hadoop,
and mpi_queue do not support environments (yet) and will
throw an error if attempted.
Fix merge.
Cleaned up stdout messages to be a little more verbose and visually consistent.
Added environment variables to docs.
Removed comments from variable example.
No need to pass environment to wrapper generation.
Removed batch_job_submit entirely, since only batch_job_submit_simple is used at all.
batch_job_submit_simple -> batch_job_submit
Pass environment from makeflow to batch_job as a struct list of name=value.
Update docs to correspond to behavior.
Propagate environment variables to batch_job_chirp.
Added test for passing environment vars makeflow->wq.
No quotes.
Add iteration methods to nvpair.
Added nvpair_export.
Pass environment using an nvpair instead.  (much simpler)
Simplified Condor and SGE implementation to handle quoting correctly.
Reduce repeated code for environments.
Backslashes to ensure env is evaluated by task.
Cleaned up and documented cluster support, so that we use a consistent
mechanism across batch types.
Fixed up test.