fix(users): make validators work with angular 1.3

the way validators are working is changed since 1.3rc1
fix(mentions): sort users in list

and limit them to 5

SD-656 SD-743
feat(tasks): Task assignment implemented.

SD-728
SD-733
fix(tasks): fixed minor issues.
fix(desks): Fixed desks service.
fix(planning): Updated coverages to use new assignee-box.
feat(desks): add wizard for desk editing
feat(desks): fix message handling in wizard
fix(desks): improve the code for adding desks
fix(desks): rebase and fix wizard first step