Tutorials/CNTK_208_Speech_Connectionist_Temporal_Classification.ipynb: fix Py 2 compatibility

Tutorials/CNTK_208_Speech_Connectionist_Temporal_Classification.ipynb

@@ -43,11 +43,11 @@
     "data_dir = os.path.join(\"..\", \"Tests\", \"EndToEndTests\", \"Speech\", \"Data\")\n",
     "print(\"Current directory {0}\".format(os.getcwd()))\n",
     "\n",
-    "try:\n",
+    "if os.path.exists(data_dir):\n",
     "    if os.path.realpath(data_dir) != os.path.realpath(os.getcwd()):\n",
     "        os.chdir(data_dir)\n",
     "        print(\"Changed to data directory {0}\".format(data_dir))\n",
-    "except FileNotFoundError:\n",
+    "else:\n",
     "    print(\"Data directory not available locally. Downloading data.\")\n",
     "    try:\n",
     "        from urllib.request import urlretrieve\n",