AOD parallel jobs

[gmao-jstassi]

The AOD job processing logic in the GEOSdas.csm file needs to be cleaned up.

In the 3DVar case, AOD can be run in parallel with GSI if enough CPUs are available for both. Otherwise, AOD should be submitted as a separate job, and GCM processing should be held up until AOD completes. This logic is pretty much already in the code.

In the ensemble case, AOD needs to be run prior to GSI processing. There is no need to run it as a separate job. It just needs to be run and completed prior to starting the GSI. It cannot be run in parallel with the GSI.