Visual Studio 2014 support for node v0.10.x series

Work in progress to get node v0.10.x working against Visual Studio 2014

 - [ ] figure out what changed with getenv/setenv behavior with 2014 runtimes (https://github.com/mapbox/node-srs/issues/48)
 - [ ] try to get gyp 2014 patch accepted upstream - https://code.google.com/p/gyp/issues/detail?id=446&q=2014


@springmeyer 
For 32/64bit builds we should think about how to make the `\\x64\\` part of the path target arch agnostic.
The paths are: `C:\Program Files (x86)\Windows Kits\8.1\bin\[x86|x64]\ctrpp.exe`.
 But I couldn't find variable within `configure` that outputs [x86|x64], as `target_arch` gives  `ia32` for x86 builds.
At least the 32bit builds complete succuessfully, even with `x64\ctrpp.exe`.
Don't know if there will be problem later on.