Update to use widop/http-adapter version 1.1+

This change reflects the change in widop/http-adapter which happened in version 1.1.
Before this version, $response was a string (the HTTP response). Now the response is wrapped in a class,  and the old content is extracted with method getBody().
Can your move it to the `require-dev` section? Basically, installing the http adapter is not mandatory. You can use the library without using service (only the map or places autocomplete which does not require the http adpater). IMO, update the doc about how install this additional library is better.