Update and shorten example of usage of add_space function

Change the order of arguments to the function to name , space to make it a bit more readable

examples/searchcv.ipynb

@@ -170,7 +170,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 2,
    "metadata": {
     "collapsed": false,
     "deletable": true,
@@ -184,7 +184,7 @@
      "text": [
       "0 0.236842105263\n",
       "1 0.236842105263\n",
-      "2 0.236842105263\n",
+      "2 0.947368421053\n",
       "3 0.973684210526\n",
       "4 0.973684210526\n",
       "5 0.973684210526\n",
@@ -212,20 +212,18 @@
     "X, y = load_iris(True)\n",
     "X_train, X_test, y_train, y_test = train_test_split(X, y, train_size=0.75, random_state=0)\n",
     "\n",
-    "search_space = {\n",
+    "opt = BayesSearchCV(SVC())\n",
+    "\n",
+    "# add instance of a search space \n",
+    "opt.add_spaces('space_1', {\n",
     "    'C': Real(1e-6, 1e+6, prior='log-uniform'),\n",
     "    'gamma': Real(1e-6, 1e+1, prior='log-uniform'),\n",
     "    'degree': Integer(1,8),\n",
     "    'kernel': Categorical(['linear', 'poly', 'rbf']),\n",
-    "}\n",
-    "\n",
-    "opt = BayesSearchCV(SVC())\n",
-    "\n",
-    "# provide instance of search space \n",
-    "opt.add_spaces(search_space, 'svc')\n",
+    "})\n",
     "\n",
     "for i in range(16):\n",
-    "    opt.step(X_train, y_train, 'svc')\n",
+    "    opt.step(X_train, y_train, 'space_1')\n",
     "    # save the model or use custom stopping criterion here\n",
     "    # model is updated after every step\n",
     "    # ...\n",

skopt/searchcv.py

@@ -276,7 +276,7 @@ def __init__(self, estimator, search_spaces=None, optimizer_kwargs=None,
             # account for the case when search space is a dict
             if isinstance(search_spaces, dict):
                 search_spaces = [search_spaces]
-            self.add_spaces(search_spaces, range(len(search_spaces)))
+            self.add_spaces(range(len(search_spaces)), search_spaces)
 
         self.n_iter = n_iter
         self.random_state = random_state
@@ -348,7 +348,7 @@ def _check_search_space(self, search_space):
                 "Search space should be provided as a dict or list of dict,"
                 "got %s" % search_space)
 
-    def add_spaces(self, spaces, names):
+    def add_spaces(self, names, spaces):
 
         self._check_search_space(spaces)