Renamed CreateConfirmableCommand to InsertConfirmableCommand.
Introduced the CreateCommand class.
Introduced the properties of CreateCommand.
Renamed CreateCommand to InsertCommand.
Implemented the ExecuteAsync(User) method.
Implemented the ExecuteAsync(Article) method.
Implemented the ExecuteAsync(Keyword) method.
Implemented the ExecuteAsync(Bookmark) method.
Merge branch 'insert-command'