MSVS 2015 support

[paulprins]

Ported some changes from the tjanczuk/edge to move to msvs 2015 (from 13). I also switched up the prebuilt library numbers to use the electron version numbers. Also this is working with 1.6.11 for both 32 & 64 bit).

Note: Going forward that the prebuilt version numbers are for Electron, not node.

[kexplo]

392a032
why did this?
I want the electron-edge will be compatible even if the electron is updated. (Until the node version of the electron goes up)
another commit is good. thanks

[paulprins]

I did this because electron-builder was rebuilding electron-edge with the node based versions. Yet when I built out the *.node libraries I used the following script:

node-gyp rebuild --target=1.6.11 --arch=ia32 --dist-url=https://atom.io/download/atom-shell --module_path=lib/ --python=python2.7 --msvs_version=2015
node-gyp rebuild --target=1.6.11 --arch=x64 --dist-url=https://atom.io/download/atom-shell --module_path=lib/ --python=python2.7 --msvs_version=2015

Changing the folder numbers to match the target took care of the rebuilding. I could be misunderstanding how that process works (I did not dig in to deeply with it).

It was also built with node v6.5.0