Support .nsproj file so this package works in NTVS as well #5

I'm now working on a Node project using NTVS: Node Tools for Visual Studio. Projects here don't have a .csproj' file, but a.nsproj` file instead. But when I use config like this in such a project:

checkVSIncludes(['/client/less/*.less', '/**/*.ts']);

A error is return:

 Error: No .csproj was found in the current working directory, check-vs-includes cannot run!

Pretty logical actually. But it would be nice if .nsproj was also supported out-of-the box. For instance fall back to looking for a .nsproj file if no '.csproj` file is found.

Note: as a workaround for now you can use the feature that we can specify an explicit file name:

checkVSIncludes(['/client/less/*.less', '/**/*.ts'], , {}, 'BuyCo.njsproj');

That works!