SVG support on Windows?

Glad to see [this PR adding SVG](https://github.com/Automattic/node-canvas/pull/1206) landed, but it doesn't appear to work on Windows when using a standard `npm install canvas`

So I looked at the binding.gyp and saw options for windows and that librsvg was false by default, so tried `node-gyp rebuild --with_rsvg=true` but it complains that it's missing headers etc. for librsvg:

```
fatal error C1083: Cannot open include file: 'librsvg/rsvg.h': No such file or directory
```

I found the librsvg files built for windows with dlls, src and headers etc on the same ftp server as gtk but not sure where to put them? Tried just copying them into c:\gtk at the appropriate places but rebuild still failing

Also tried putting them in c:\librsvg, I'm not a C++ dev though so really just guessing and flailing in the dark here, any ideas?