old_contents: from mailjet.connection import Connection
  import json
  
  class Api(object):
      def __init__(self, connection=None, api_key=None, secret_key=None):
          if not connection:
              connection = Connection.get_connection(api_key, secret_key)
  
          self.connection = connection
  
      def __getattr__(self, method):
          return ApiMethod(self, method)
  
  class ApiMethod(object):
      def __init__(self, api, method):
          self.api = api
          self.method = method
  
      def __getattr__(self, function):
          return ApiMethodFunction(self, function)
  
      def __unicode__(self):
          return self.method
  
  class ApiMethodFunction(object):
      def __init__(self, method, function):
          self.method = method
          self.function = function
  
      def __call__(self, **kwargs):
          if kwargs.pop('method', 'GET') == 'POST':
              postdata = kwargs
              options = None
          else:
              options = kwargs
              postdata = None
  
          response = self.method.api.connection.open(
              self.method,
              self.function,
              options=options,
              postdata=postdata,
          )
          return json.load(response)
  
      def __unicode__(self):
          return self.function
  
  
new_contents: from mailjet.connection import Connection
  import json
  
  class Api(object):
      def __init__(self, connection=None, api_key=None, secret_key=None):
          if not connection:
              connection = Connection.get_connection(api_key, secret_key)
  
          self.connection = connection
  
      def __getattr__(self, method):
          return ApiMethod(self, method)
  
  class ApiMethod(object):
      def __init__(self, api, method):
          self.api = api
          self.method = method
  
      def __getattr__(self, function):
          return ApiMethodFunction(self, function)
  
      def __unicode__(self):
          return self.method
  
  class ApiMethodFunction(object):
      def __init__(self, method, function):
          self.method = method
          self.function = function
  
      def __call__(self, **kwargs):
          if kwargs.pop('method', 'GET') == 'POST':
              postdata = kwargs
              options = None
          else:
              options = kwargs
              postdata = None
  
          response = self.method.api.connection.open(
              self.method,
              self.function,
              options=options,
              postdata=postdata,
          )
  
          if response.msg == u'No Content':
              return None
  
          return json.load(response)
  
      def __unicode__(self):
          return self.function
  
  
subject: Return None when mailjet responds with 'No Content', fixes #11