Git Submodule Fix

@harlanhaskins,

In commit 2d87d2fe45f20a6699b71eb92a1213e4410e552a you removed the `AFNetworking` and *attempted* to use a git submodule in place. Unfortunately, there were multiple problems with the commit.

First, you failed to provide a `.gitmodules` file which defines each submodule, it's path, and it's URL. So, while a submodule did exist

![](http://i.imgur.com/YQzpDuI.png)

it was linked to nothing. 

I've rectified this by properly defining the submodule so that it is linked to the [AFNetworking repository](https://github.com/AFNetworking/AFNetworking).

![](http://i.imgur.com/x4jHZFr.png)

In addition, the Xcode project was unable to find the AFNetworking files because (I assume) they were never re-added to the project from their new location after the implementation of the submodule - they were previously located in `./CSH WebNews/AFNetworking` but now reside in `./CSH WebNews/AFNetworking/AFNetworking`.

I've also gone ahead and added documentation for users looking to build the project themselves.

&mdash; @citruspi