Allow configurable retry of preprocess and postprocess actions on Pulsar side.

Uses Kombu style retry parameters since we are already exposing those for message publish retrying. See job_managers.ini.sample for specific new options.

Lots left to do - integration test of this and retry framework for client side actions.
Correctly respond to remote status code when uploading/downloading files with Curl.

If something went wrong before during pull down results from Galaxy - it would just take the error json as the input file. Likewise - it would not fail jobs if the postprocessing failed to publish - leaving empty green files in the Galaxy history.