Escape whitelisted query parameters

- Query params are not escaped, so if quotes are present in the params, the output resembles: `<link href="http://www.mywebstore.com/our_resources/?page=5&keywords="here be dragons"" rel="canonical" />` (breaks the HTML)
- Escaping the params produces: `<link href="http://www.mywebstore.com/our_resources/?page=5&keywords=%22here+be+dragons%22" rel="canonical" />`
- `require 'cgi'` is unnecessary because Rails already requires that library, but I've included it to be explicit (Ruby will simply skip it since it's already loaded)
- Added a test to ensure query params are escaped

Shoot any questions my way. Cheers!