Sorting sorting arrows
Created by: birdsarah
Fixes for sorting arrows:
- 2 -> 1 on Decided Date & Review Date (caused by insertion of class=sort twice)
- 0 ->1 on ID and Last Modified (caused by not specifying the - as these columns are sorted in reverse order)
Added a test that tries sorting each column on each page and confirms the presence of only one sort class in the summary-list-table.