title: How to force app engine upload node_modules
body: <p>In my project we are using nodejs with typescript for google cloud app engine app development. We have our own build mechanism to compile ts files into javascript ,then collect them into a complete runable package, so that we don't want to relay on google cloud to install dependencies, instead we want to upload all node packages inside the node_modules to google cloud.<br/><br/>
  But it seems google cloud will always ignore the node_modules folder and run npm install during the deployment. Even I tried to remove 'skip_files: - ^node_modules$' from app.yaml, it doesn't work, google cloud will always install packages by itself. <br/><br/>
  Does anyone have ideas of this of deploy node app with node_modules together? Thank you.</p>