Restructure the examples project

At the moment the current organisation of the IGListKit iOS Examples workspace is separated in to large view controllers/views/section controllers etc folders. For me it seems to be quite tricky to find out which View Controllers and Section Controllers are used for a specific cell in the main UICollectionView.

I reckon that the structure of the project should reflect the UI of the app, like this:

```
- Tail Loading
- View Controllers
- Views
- Section Controllers
- Models
- Search Auto Complete
- View Controllers
// etc
```

There may be some issues of Section Controllers that are used in more than one part of the app, but I think this will be much more user friendly approach. I currently have my own app organised in a similar way to this and it works great.

Thoughts?