Unify the controller configuration dialogs.

Prior to this, the configuration for the GameCube controller port devices were in the Config->Gamecube menu, whereas the Wiimotes had their own menu. This unifies the ports into the same dialog. Here is how it looks:
![Imgur](http://i.imgur.com/PiWQlhh.png)

I made this PR to begin discussion and hear opinions on whether or not this is a good idea. This UI can be changed in the future to accommodate suggestions in another PR as the goal of this pull request was to join all of the controller menu logic into one central area.

If this is seen as a good idea, then a new icon will need to be made, as a picture of a Wiimote+Nunchuk wouldn't visually describe the unified menu accurately.