Change list of light buildings

- The building types residential, house, detached, terrace and
  apartments are no longer light.
- The building types roof, service, shed, shelter, cabin,
  storage_tank, tank, support, glasshouse, mobile_home, kiosk
  silo, canopy and tent are now light.

This commit is based on a comment by @vincentdephily:
https://github.com/gravitystorm/openstreetmap-carto/pull/434#issuecomment-38928265

This closes #68 and supersedes #434.