Propose new config value to run harvest sources by external apps

[avdata99]

This setting value establishes a harvest source as inactive and will allow us to simply harvest these marked sources to harvest externally

[adborden]

Why do we modify the dataset state? I would expect that an inactive harvest source with a non-CKAN harvest_app would not be harvested either by CKAN or an external harvester. Seems instead of mutating state, we should be hooking into the harvest process and keying off of harvest_app then.

[avdata99]

Why do we modify the dataset state? I would expect that an inactive harvest source with a non-CKAN harvest_app would not be harvested either by CKAN or an external harvester. Seems instead of mutating state, we should be hooking into the harvest process and keying off of harvest_app then.

If I just hook into the harvest process we continue needing CRON (or some tool) to start the harvest process. I think is better to let external apps to start the harvesting process in its own way.

Also, If I mutate the state the current jobs will stop automatically. This is good.

What do you think @akariv?