Dsub python library should parameterize console output

[bfcrampton]

Currently calling dsub.run(...) from python causes output of the following form in stdout:

Launched job-id: echo--bryancrampton--171108-161028-235004
To check the status, run:
  dstat --provider local --jobs 'echo--bryancrampton--171108-161028-235004' --status '*'
To cancel the job, run:
  ddel --provider local --jobs 'echo--bryancrampton--171108-161028-235004'
echo--bryancrampton--171108-161028-235004

Similarly, ddel outputs: Found N tasks to delete

The dsub python library should either not print like this, or parametrize the output writer in some way. Currently removing this output requires a hacky re-routing of sys.stdout.