Will use the pegasus.change.dir profile option via `config.yaml`
instead.

This reverts commit c26ca54f.

The BLAHP submit wrapper creates a temp directory and cd's there
before running the executable. This breaks Pegasus jobs for a
sharedfs site as it expects to be in the shared-scratch dir
via the `remote_iwd` Condor ClassAd.  This dir is available via
the PEGASUS_SCRATCH_DIR env variable in the job, so cd there as a
workaround.

This reverts commit 1c068ff3.

Updated workflow_module dependency handling.  Updated download_fastq script.  Added Ladunga experiment select mongodb pipeline.

Added download script.  Updated job yaml.  Updated module yaml.  Add executable loading to workflow code.  Updated database validation for new inputs.