Add batch_number back into SAAABO NEHVI tutorial

Summary:
As titled

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: dme65

Differential Revision: D30943852

fbshipit-source-id: 2170bcadab19c7ef99a4f3d496c88da77a630777

tutorials/saasbo_nehvi.ipynb

@@ -1038,7 +1038,8 @@
         "\n",
         "n_results = N_BATCH*BATCH_SIZE + N_INIT\n",
         "\n",
-        "sc = axes.scatter(train_obj[:, 0], train_obj[:,1], c=df.trial_index.values, alpha=0.8)\n",
+        "batch_number = df.trial_index.values\n",
+        "sc = axes.scatter(train_obj[:, 0], train_obj[:,1], c=batch_number, alpha=0.8)\n",
         "axes.set_title(algos[0])\n",
         "axes.set_xlabel(\"Objective 1\")\n",
         "axes.set_ylabel(\"Objective 2\")\n",