Editorconfig and Rebracer.xml

I added these two files to the root of our solution. For developers without the extensions installed, they have no effect. These two files are really useful for people that work on projects/work with different coding standards. They will automatically configure your editor to the coding standards of the solution when you open it and restore your settings to your defaults when you close.

**Editor Config**

This file defines spacing and tabs for the files in the solution. There are plugins available for pretty much every editor and IDE out there including Visual Studio, Vi, Emacs and even Notepad++. 

For more information, got to http://editorconfig.org/. The Visual Studio extension is on [GitHub](https://github.com/editorconfig/editorconfig-visualstudio) and can be installed from the [Visual Studio Gallery](https://visualstudiogallery.msdn.microsoft.com/c8bccfe2-650c-4b42-bc5c-845e21f96328)

**Rebracer**

Thanks to @SLaks for pointing this out. Rebracer sets all of the code formatting rules for the project when you open the solution and restores your defaults when you close. I have gone through all the settings and set them to the NUnit coding standard. If anyone finds that they are incorrect, if you have the extension installed, you simply need to open the Visual Studio options and change the settings. The changes will automatically be saved out to the Rebracer.xml file.

Rebracer is also on [GitHub](https://github.com/SLaks/Rebracer) and can be installed from the [Visual Studio Gallery](https://visualstudiogallery.msdn.microsoft.com/410e9b9f-65f3-4495-b68e-15567e543c58)

If this pull request is accepted, I will add this info to the developer documentation.