Add ability to set mapbox tile url

Author: ansis

src/layer.js

@@ -41,7 +41,7 @@ mapbox.layer.prototype.url = function(x, callback) {
 
 mapbox.layer.prototype.id = function(x, callback) {
     if (!arguments.length) return this._id;
-    this.url('http://a.tiles.mapbox.com/v3/' + x + '.jsonp');
+    this.url(mapbox.MAPBOX_URL + x + '.jsonp');
     this.named(x);
     this._id = x;
     return this.refresh(callback);

src/load.js

@@ -33,7 +33,7 @@ mapbox.load = function(url, callback) {
 
     // Support bare IDs as well as fully-formed URLs
     if (url.indexOf('http') !== 0) {
-        url = 'http://a.tiles.mapbox.com/v3/' + url + '.jsonp';
+        url = mapbox.MAPBOX_URL + url + '.jsonp';
     }
 
     wax.tilejson(url, function(tj) {
@@ -46,7 +46,7 @@ mapbox.load = function(url, callback) {
             lon: tj.center[0]
         };
 
-        tj.thumbnail = 'http://a.tiles.mapbox.com/v3/' + tj.id + '/thumb.png';
+        tj.thumbnail = mapbox.MAPBOX_URL + tj.id + '/thumb.png';
 
         // Instantiate tile layer
         tj.layer = mapbox.layer().tilejson(tj);

src/map.js

@@ -1,5 +1,6 @@
 if (typeof mapbox === 'undefined') mapbox = {};
 
+mapbox.MAPBOX_URL = 'http://a.tiles.mapbox.com/v3/';
 
 // a `mapbox.map` is a modestmaps object with the
 // easey handlers as defaults