Remove npm auto-upgrade

- There have been some bugs around updating npm to the latest version
recently, so let's leave managing npm itself up to the end user

script/setup

@@ -12,9 +12,6 @@ cd "$(dirname "${0}")/.."
 # Install virtualenv
 pip install pipenv
 
-# Update npm
-npm install -g npm
-
 if ! type sass > /dev/null; then
   if type gem > /dev/null; then
     echo 'installing a sass compiler...'