Fixed a whole bunch of issues and added some stuff

+ Fixed #1 - Show message on failure and when success isn't obvious from
changes in the UI.
+ Fixed #2 - Added a jQuery plugin (jquery.grade.js) to show importance
visualy instead of having a number.
+ Fixed #7 - Reordered the main menu to have views first since those are
usually the most interesting pages. Template and Users are last since
those aren't often used.
+ Fixed #11 - Added a reassign button to make it possible to reassign a
task to someone. An assigned task only shows to the assignee and the
owner of the task.
+ Fixed #12 - Added a button to reopen a completed task, before it's
cleared at least.
+ Fixed #13 - Added an option to suspend a task a fixed number of days,
1,2,3,7,30