Few missing things

[ilyapuchka]

I've tried to use this yesterday and noticed two missing things:

• to generate project the Sources folder should contain folder with name of the target and it should contain Decoder and Encoder subfolders. Same about tests
• the template code is invoking let container = KeyedContainer(data: self.data, codingPath: self.codingPath, userInfo: self.userInfo) but there is no data property defined on this type