Changed default behavior to not force install

Author: dmarx

pytti_5_beta.ipynb

@@ -363,7 +363,7 @@
         "  !mkdir -p images_out\n",
         "  !mkdir -p videos\n",
         "\n",
-        "force_install = True #@param{type:\"boolean\"}\n",
+        "force_install = False #@param{type:\"boolean\"}\n",
         "if not everything_installed or force_install:\n",
         "  install_everything()\n",
         "elif everything_installed:\n",