Replace reference with place_id or placeid

Closes #11. The Places API deprecated the _reference_ parameter on June 24, 2014 and it will no longer be accepted starting June 24, 2015. Requests should instead use the _place_id_ returned by a Search request, which can be passed to a follow-up Detail request with the _placeid_ parameter. (Please note the lack of underscore in the parameter for the Detail request.) [Source](https://developers.google.com/places/documentation/search)