Syncing will take more time as number of past jobs grows

[stevejalim]

In production, we don't delete completed jobs. As such, the amount of time and number of API calls made to sync against Smartling will only go up. At some point, without warning, this is likely to bite.

We should get ahead of this.

Ideas:

• Don't re-check status of Completed jobs, saving us an API call for each -- this will only work if we never reopen completed jobs
• See if we can filter the API call made to smartling to exclude Completed-status jobs -- but this would stop us changing state from In Progress to Completed, so it's more a case of excluding jobs that are Completed and older than a safety window of X hours (where X is more than a weekend, to be on the safe side)
• More to come - suggestions welcome