Zoom to extent in map constructor

[thisisaaronland]

It would nice to be able to specify a bounding box in the constructor and have mapzen.js take care of the rest, rather than having to do the following:

var map = L.Mapzen.map('map', {
          center: [ 37.764943, -122.419496],
          zoom: 13,
          scene: L.Mapzen.BasemapStyles.TronNoLabels
        });

var bbox = '-122.419304,37.764832,-122.419304,37.764832'.split(',');

var sw = L.latLng(bbox[1], bbox[0]);
var ne = L.latLng(bbox[3], bbox[2]);
var bounds = L.latLngBounds(sw, ne);

map.fitBounds(bounds)