[Requirement] Add existence check when adding a requirement mode
When adding a new mode in the mode aspect, the system has to check whether that mode name already exists.
(from redmine: issue id 2929, created on 2017-04-12, closed on 2017-05-16)
When adding a new mode in the mode aspect, the system has to check whether that mode name already exists.
(from redmine: issue id 2929, created on 2017-04-12, closed on 2017-05-16)