Inital version of the project system copied from https://github.com/mavnn/NuGetPlus/blob/master/NuGetPlus.Core/ProjectSystem.fs
Trying the ProjectSystem approach discussed in #216
Try to make the project system as dumb as possible we'll use TDD and implement only what we need - references #216
Try to detect subfolders
Using xpath to retrieve all files of a project - references #126
Merge pull request #220 from fsharp/ProjectSystem

Project system