feat(media): improve ui
fix(users) : hide hints when inserting new user

Remove hints for "required" fields when creating new user, and instead
of hints, show asteriks
fix(users): hide required fields on user preview

Show "required" field only when it is required, not always
feat(users): add user list sorting

+ change sd-sort directive
+ add sd-sort directive to user list

SD-242
fix(tests): add missing filter into spec