Support waypoints for overall distance calculation

[sandraa-nestor]

Support waypoints for overall distance calculation

Current behaviour:

Google::Maps.route('London', 'Cambridge').distance
 => {"text"=>"61.2 mi", "value"=>98570}
Google::Maps.route('London', 'Cambridge',  waypoints: 'Luton').distance
 => {"text"=>"34.1 mi", "value"=>54902}

#distance method only returns distance from London to Luton

Expected behaviour:
Route with waypoint returns distance 71.1 miles (sum of London-Luton + Luton-Cambridge)