fix(users): extend userList service

and make use of it in mentions
feat(preferences): user prefrences ui
fix(notifications): add styling to notification label
fix(checkbox): Reverted checkboxes to native ones.

SD-688
fix(authoring): update styling for widgets
Merge remote-tracking branch 'ozan/checkbox-fix' into devel
Merge remote-tracking branch 'nikola/devel' into devel
fix(mentions): remove predicting the content

because of badly positioned elements
fix(notification): display unread items
fix(tasks): Fixed wrong date assigning.

SD-72
Merge remote-tracking branch 'ozan/task-date-fix' into devel
feat(tasks): task preview
feat(tasks): Desk switch enabled.

SD-734
feat(task): task preview fix
feat(notification): add link to item

SD-722 SD-656
fix(mentions): remove unused file
Merge remote-tracking branch 'petr/devel' into devel
chore(bower): update angular to rc2
fix(notification): add style to links
Merge remote-tracking branch 'nikola/devel' into devel