[WIP] Windows deployment

[dereklieu]

Sets up windows deployment
Todo: set up CI to run the deployment.

[sethvincent]

Nice, I can try this out on my windows machine.

[dereklieu]

Update on this PR:

Mapnik dependency

I rolled up the @mojodna/observe-tools module out of package.json and included it as a file in lib. I just removed the icon processing step which allowed me to get rid of the mapnik dependency altogether (we're not using icons anywhere as of now, and I wanted to get to a working WIN installer). There are a couple of methods for converting svg to png that can take advantage of the hybrid node/chrome electron environment, all of which take some time that I'd rather avoid right now. cc @sethvincent @mojodna

Bundling

Bundling works and produces a file with a bunch of dll files, licenses, and an .exe that looks like it should work. I've zipped that up and sent it to @sethvincent for him to test out on his WIN machine.

Installer

I had to package the windows build using electron's asar archive format in order to create the installer. With asar set to false, creating the installer hung for over an hour before I killed it.

Using the asar format on the mac build has created issues with native dependencies. Waiting to see how this does.