migration to gl js

[hrecht]

I worked on #58 for a bit at Code for DC - this branch migrates the map to mapox-gl.js and draws the bike lanes.

[alulsh]

Thanks for getting this started @hrecht! Just granted you write access to the repo - mind pushing this directly as a feature branch in another PR instead of a PR from you fork? Will make the workflow much easier.

A couple of things to fix in this PR before we can merge:

• Fix the right hand corner zoom control - at the moment the div at the top covers it and you can only zoom out, not zoom in
• Fix the buffers

Once this is PR'd as a work in progress (WIP) PR directly to this repo, others can add commits to the branch and tackle the above tasks.

Thanks again for working on this @hrecht!