Enable JSONP, CORS for API requests - Limit per_page to 100 for sanity

Allows either CORS or JSONP access to the API for cross-domain options.  Also limits the per_page to 100 for some sanity.  Currently you can download the entire database with `curl http://www.refugerestrooms.org/api/v1/restrooms.json?per_page=15000 > restrooms.json` -- must be mean on your heroku :)
Use the new Ruby 1.9 hash syntax.