Add "kpm wrap" command

- Add CsprojDumper, a tool used to dump csproj references
- "kpm wrap" creates project.json wrappers for csprojs in 'wrap' folder
- "kpm wrap" updates global.json to include 'wrap' folder as sources
- Project references are added based on output assembly name
"kpm restore" only caches http responses with success status code
Expose the project build output folder to project.json