Sorting submissions and reviews

Allow sorting on all columns in the 'Submissions' and 'Reviews' tab.

The only option now is sorting (asc/desc) on ID, and only in the 'Submissions' tab.

I'd like to be able to quickly find a group, or see what the newest submission is (ID is probably the same order as Date, but still).

(b-table has a sortable key or similar that can be easily enabled to allow users to sort by them)