Wire up gh-pages branch

[JohnTigue]

For the GitHub Pages site, this would be a simple leaflet deploy with a checkboxed layer switcher which would let folks see any combination of the various boundaries.

A goal is to have this branch be, hopefully completely, the same code that would run if someone were to clone the repo and runs the static code locally. This is simply a reminder to get the data experience-able at http://codeforseattle.github.io/seattle-boundaries