update
Merge branch 'master' of github.com:stubbles/stubbles-webapp-core
upgrade stubbles/core and stubbles/input to latest bugfix releases
Use status code 504 for external auth provider failures, fixes #69

The previously used status code 503 is for problems with the server itself,
but what we want to depict here is a failure in an upstream server, where
504 is more appropriate.
Invalid request should trigger a 400 Bad Request, fixes #70

The uri extracted from request data (i.e. $_SERVER) might be invalid because
the issued request is erronous or the requestor tries to check if invalid
data is handled correctly. Until now such cases where detected with the
MalformedUriException, but as it was not catched it lead to a 500 Internal
Server Error response. With this fix the exception is catched, and a 400
Bad Request response is triggered instead.