Fix tag sorting and filtering options
Currently the sort-by dropdown on the tags page has no "default" sort name, so the button looks awkward when no option is selected, plus once you've selected an option there is no way to get back to the default sort option. Because it is not labeled I'm not even sure what the default sort is. (I'm guessing it's ordered by creation date)
I propose we give a name to the default sort option and make it selectable in the dropdown.
There are also some CSS issues to work out with the buttons here: