UI change to facilitate varying rubric feature:

1 in the student_task list, "current stage" shows the
deadline name, if there is one (otherwise is shows the
default keywords like "submission", "review"...)
2 in the student_task list, "current stage" also gives
hyper link to the description url for this phase, if
there is one
3 in the student_task view, the assignment name gives
hyper link to the assignment description, if there is
one