Only try to parse as JSON if the JSON content type
        header is set.

def initialize(self,*args,**kwargs):
        """
        Only try to parse as JSON if the JSON content type
        header is set.
        """
        super(JSONHandler,self).initialize(*args,**kwargs)
        content_type = self.request.headers.get('Content-Type', '')
        if 'application/json' in content_type.lower():
            self._parse_json_body_arguments()