fix(users): fix user update
test(users): add test for username validation
fix(users): Fixed removing user in preview area after a delete operation.
fix(users): Fixed a wrong scope operator in sdUserUnique.
fix(users): fixed activity callbacks, added returning activity item as parameter.

close #172
fix(users): Fixed displaying less users after deleting a user.
fix(users): Added previously forgotten criteria parameter to fetchUsers.

close #184