erp5_api_style: API call set proper header for JSON Content type

bt5/erp5_api_style/DocumentTemplateItem/portal_components/document.erp5.jIOWebSection.py

@@ -46,6 +46,7 @@ def convertTojIOAPICall(function):
     Log the call, and the result of the call
     """
     try:
+      self.REQUEST.response.setHeader("Content-Type", "application/json")
       retval = function(self, *args, **kwd)
     except Unauthorized, e:
       LOG('jIOWebSection', INFO, 'Converting Unauthorized to Unauthorized error mesage in JSON,',