Pswadi/buddy approval for release

The tag / SHA specified in the deploy will be used for checking if the same deploy to another production stage was already approved in last 4 hours. If so, the buddy will be "carried forward" for the new stage.   BUDDY_CHECK_GRACE_PERIOD decides how long we want to search for.

This does not start the queued up deploys, yet.

/cc @zendesk/samson @grosser @steved555 

### References
 - Jira link: 

### Risks
 - Buddy approval anomalies?
parentheses for clarity:
```
deploy.buddy = (last_d.buddy == @user ? last_d.job.user : last_d.buddy)
```