init() should be backwards compat with older API

Ref jupyter#196

(c) Copyright IBM Corp. 2016

nb-extension/js/init/init.js

@@ -155,6 +155,16 @@ define([
     }
 
     return function(config) {
+        var baseURL;
+        if (typeof config === 'string') {
+            // backwards compatibility with old API, which took `baseURL` as first argument and
+            // optional `config` as second arg
+            baseURL = config;
+            config = arguments[1] || {};
+        } else {
+            baseURL = config.IPython ? config.IPython.notebook.base_url : '/';
+        }
+
         // if we are not in Jupyter notebook, need to create shims for compatibility
         if (!config.IPython) {
             shimIPython(config);
@@ -176,7 +186,6 @@ define([
         // expose suppressErrors, false by default to display errors
         window.Urth.suppressErrors = config.suppressErrors;
 
-        var baseURL = config.IPython ? config.IPython.notebook.base_url : '/';
         isServerExtensionAvailable(baseURL + COMPONENTS_DIR, function(isAvailable){
             console.log('Server extension is ' + (isAvailable ? '' : 'NOT ') + 'available!');