Explicitly allow PIL to be installed from external sources.

Author: alancutter

tools/python/requirements.txt

@@ -7,4 +7,6 @@ selenium
 # Requirements for using -x
 pyvirtualdisplay
 pyscreenshot
+--allow-external=PIL
+--allow-unverified=PIL
 PIL

tools/python/setup.sh

@@ -29,6 +29,10 @@ EOF
 
   if virtualenv --system-site-packages .; then
     echo -e;
+    (
+      source bin/activate
+      pip install --upgrade pip
+    )
   else
    cat <<EOF
 Was unable to set up the virtualenv environment. Please see output for errors.