- Moved admin/task_tags to admin/task-tags because that's apparently how we do urls.
- Fixed autocomplete showing up only under the first tag form in the page.
- Added "number of tasks" column to admin/task-tags page and made it and "Operations" column fixed width.
- Disabled deletion of algorithm tags that are in use.
- Allow ( and ) in algorithm tags. (for Sortare O(NlogN))
- Made age_group no longer depend on the contest.