Begin Heat Map

1) Add socket.io for seamless client-server event interaction
2) Add node-geocoder for geocoding zip codes returned with the
signatures api

Signed-off-by: Alex Dove <alexdovethgreat@gmail.com>
First cut at google maps heat map

1) Use geocoder to map zip codes to lat,lon pairs
2) Use socketio to send lat,lons when they are done being geocoded to
the client, and update the ui upon receiving new coords
3) ignore sass cache
Add link to heatmap on petitions page

Sweet!