Update ca-ns-halifax.json

Sent an email to the city of Halifax and they actually just came out with a new open data site. It gives a nice .zip shapefile format instead of the previous one. Hopefully it'll work better. In the email she actually confirmed the new site as being www.halifax.ca/opendata/ although it's not loading for me. Doing a search in Google confirms this but again, doesn't load. The old one will be taken down October 31st according to the email I received so updating the links anyways. They'll sort out their servers I'm sure. Data link works.