Deployment tracking

[davidsiaw]

This PR aims to consolidate tracking to a cron job that will run every several minutes to poll the statuses of all deployments

This is to

• avoid using the current recursive system
• avoid getting rate limited by having too many status polls
• make it easier to maintain deployment errors and tracking

How to test

There are 2 things to test here, migration of the old barcelona stacks and functionality of new stacks.

1. kaiser up a local barcelona on the master
2. deploy a district and then deploy the barcelona hello stack
3. update to this branch
4. re-deploy the district
5. we should have a ServiceDeploy object in rails console
6. we should be able to run bcn:deployment_check and it should say it is completed if the stack is complete or incomplete if it is not yet updated..

For new stacks, simply deploy the hello stack on the current branch, and check that bcn:deployment_check will complete the deployment notification for compleetion.