v0.7.0: UI fixes, add database migrations

* UI: Add a "Please login" notice
* UI: Add "no results" notice
* Redirect to the previous page after login
* Display result numbers in the Job page or when 0 results
* UI: Only display search form and buttons on index
* Display proper errors on the job submission page
* Add database migrations
* Implement submissions
* Log HTTP(S) listening addresses