Fix Tutorial 9 (#734)

* Add package download

* Change dev to train file

tutorials/Tutorial9_DPR_training.ipynb

@@ -8,7 +8,7 @@
     "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/deepset-ai/haystack/blob/master/tutorials/Tutorial9_DPR_training.ipynb)\n",
     "\n",
     "Haystack contains all the tools needed to train your own Dense Passage Retrieval model.\n",
-    "This tutorial will guide you through the steps required to create a retriever that is specifically tailored to your domain.\n"
+    "This tutorial will guide you through the steps required to create a retriever that is specifically tailored to your domain."
    ],
    "metadata": {
     "collapsed": false,
@@ -17,6 +17,25 @@
     }
    }
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "outputs": [],
+   "source": [
+    "# Install the latest release of Haystack in your own environment\n",
+    "#! pip install farm-haystack\n",
+    "\n",
+    "# Install the latest master of Haystack\n",
+    "!pip install git+https://github.com/deepset-ai/haystack.git\n",
+    "!pip install torch==1.6.0+cu101 torchvision==0.6.1+cu101 -f https://download.pytorch.org/whl/torch_stable.html"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -318,7 +337,7 @@
     "\n",
     "retriever.train(\n",
     "    data_dir=doc_dir,\n",
-    "    train_filename=dev_filename,\n",
+    "    train_filename=train_filename,\n",
     "    dev_filename=dev_filename,\n",
     "    test_filename=dev_filename,\n",
     "    n_epochs=1,\n",

tutorials/Tutorial9_DPR_training.py

@@ -61,7 +61,7 @@ def tutorial9_dpr_training():
 
     retriever.train(
         data_dir=doc_dir,
-        train_filename=dev_filename,
+        train_filename=train_filename,
         dev_filename=dev_filename,
         test_filename=dev_filename,
         n_epochs=1,