Add database management API calls and update crons

[howard-e]

Partially address #759 in making it easier to get a database dump from production and restoring it in staging or sandbox.

This PR adds API functions:

• Dumping postgres database
• Restoring postgres database
• Cleaning up the database dumps directory so it doesn't grow too large (defaulted to max of 28 days)

This PR adds the following cron jobs:

• Dumping postgres database every day at 00:00
• Cleaning up the dumps directory if necessary every day at 00:05

[stalgiag]

Thanks for this work! I see how this could make several tasks much easier. I left a few concerns inline. I may be overly cautious since I don't know the ansible environment well but if my understanding is correct here then I think we should add a couple of additional safeguards just to be careful.

[stalgiag]

Looks good! Thanks for addressing the feedback.

I'll leave to you to merge when you are ready @howard-e