Support running on Windows

[rib]

This would depend on #147 - Enable capturing OA metrics via MDAPI

This would involve adding support for the GYP build system (I can provide further pointers to help here based on maintaining a few other projects using GPY which also embed libraries like libuv, and libprotobuf-c)

We should also embed libproto in the gputop repo like we do for libuv and libprotobuf-c

As part of this we should also enable building and testing via AppVeyor