Re-license under ASL 2.0.
Big re-organization of www/data artifacts

- Rename html/ to www/
- Update bin/stl-download to write index.json rather than meta.json;
  change viz.js accordingly
- Update bin/stl-download to sort crimes in each month by timestamp
- Update bin/push to require both data and www destinations
- Add bin/httpd and http/httpd.conf to that runs a local Apache instance
  pointed at ${CRIMEDB_ROOT}/{data,www}
Move www/stl/ to www/d/stl/.
Bundle leaflet.css.
Add access logging to httpd.conf
Move all STL-specific JS into /d/stl/stl.js; make viz.js a module.