Better jobs view

[erik-stephens]

As an operator, I need to see all jobs with a specific status (eg running, failing, failed). As it's modeled, _status is only in the ex records:

> http $host/jobs/$job | jq '._status, ._created'
null
"2017-09-08T23:06:50.955Z"

> http $host/jobs/$job/ex | jq '._status, ._created'
"running"
"2017-09-11T13:26:08.213Z"

Trying to create job centric views from ex records is problematic because of the multiple records for the same job. If I want to filter on failed, then I only want to see the last failed job, not every failed execution for that job.

Also, the _created field is clobbered by the ex version. Being able to see the created timestamp helps identify that I'm viewing (and possibly restarting) the correct job and not an old. The _updated field is an ok workaround, so this problem is less impactful.

The api is close via the status filter on the /ex endpoint, but there is no way filter by time.

[kstaken]

This is superseded by #3770