Specify debug settings in project file 

This eliminates the complex setup step when working on the project.

Inspired by jaredpar/SaveAllTheTime@3a0d300:

>Previously the startup debugger settings were stored in the .csproj.user
>file.  This meant that a new clone of SaveAllTheTime or branch switch
>would eliminate the start up / debugging settings for the project.  By
>putting them into the .csproj directly we eliminate this problem.

>Additionally this uses the $(DevEnvDir) variable instead of hard coding
>the directory to Visual Studio directory.  This makes the setting
>tolerant to x86 versions of Windows as well as non-traditional install
>locations (some people like to install Visual Studio on the D drive).

I also changed reference paths to use the variable, and updated version numbers of referenced assemblies to 12.0.