Support for the Directions API

[Hans Knöchel]

Expose the Directions REST API. Example:

maps.getDirections({
    origin: 'Mountain View, CA',
    destination: 'San Francisco, CA',
    success: function(e) {
        Ti.API.info(e.routes);   
    },
    error: function(e) {
        Ti.API.error('Error: ' + e.error);
    },
    // Optional
    waypoints: ['Cupertino, CA', 'via:Sunnyvale, CA'],
    }
});

[Hans Knöchel]

Supported as part of #74