'Checks that a single application definition contains no invalid
or unsupported keys.
:param bytes application: The name of the application this config
is mapped to.
:param dict config: A single application definition from
the application_configuration dictionary.
:raises ValueError: if any invalid or unsupported keys found.
:returns: ``None``'

def _validate_application_keys(self, application, config):

    _check_type(config, dict, u'Application    configuration    must    be    dictionary', application)
    present_keys = set(config)
    invalid_keys = (present_keys - self._allowed_keys)
    if invalid_keys:
        raise ConfigurationError(u"Application    '{application_name}'    has    a    config    error.    Unrecognised    keys:    {keys}.".format(application_name=application, keys=u',    '.join(sorted(invalid_keys))))
    if (u'image' not in config):
        raise ConfigurationError(u"Application    '{application_name}'    has    a    config    error.    Missing    'image'    key.".format(application_name=application))
