Various tweaks

- Separated json into housing_data.js
- Separated styles into style.css
- Placed housing markers into layerGroup and added layer control
Made housing data default layer
Updated data files

Created data folder, copied in housing_data.js and
lgd_boundaries.geojson
Added simplified geojson file
Deleted old lgd_boundaries.geojson file

simplified file is much smaller and accurate enough for demo purposes
Added local gov boundaries as new map layer
Merge pull request #1 from briancleland/master

Various tweaks