add an optional host parameter. more comments

src/nest.js

@@ -1,4 +1,3 @@
-// #nest.js 
 // nest.js is a javascript wrapper to the Echo Nest 
 // [developer api](http://developer.echonest.com).
 
@@ -7,10 +6,19 @@
 var nest = {
     // This is the main object that is used
     // to call the api
-    nest: function(api_key) {
+    nest: function(api_key, host) {
+        // optionaly take in another host,
+        // for testing purposes
+        host = host || "developer.echonest.com";
         return {
+            // return the read-only `api_key`
             get_api_key: function(){
                 return api_key;
+            },
+
+            // return the read-only `host` name
+            get_host: function(){
+                return host;
             }
         };
     }