Continue even if the app.yaml file could not be parsed as the information is not critical for most actions, print a warning so the user is still aware that something is wrong.
Continue even if the app.yaml file could not be parsed as the information is
not critical for most actions, print a warning so the user is still aware that
something is wrong.

runserver implements its own checks and still fails if app.yaml is broken.

termie/google-app-engine-django,google-code-export/google-app-engine-django,hitrust/google-app-engine-django,dila93/google-app-engine-django,jackxiang/google-app-engine-django,ekkleesia3/google-app-engine-django,brian-zhao/google-app-engine-django