changes to xml_module to allow problem metadata to be added via <meta>

common/lib/xmodule/xmodule/xml_module.py

 from xmodule.x_module import XModuleDescriptor
 from xmodule.modulestore import Location
 from lxml import etree
+import json
 import copy
 import logging
 import traceback
@@ -32,7 +33,15 @@ def is_pointer_tag(xml_obj):
     actual_attr = set(xml_obj.attrib.keys())
     return len(xml_obj) == 0 and actual_attr == expected_attr
 
-
+def get_metadata_from_xml(xml_object, remove=True):
+    meta = xml_object.find('meta')
+    if meta is None:
+        return ''
+    dmdata = meta.text
+    log.debug('meta for %s loaded: %s' % (xml_object,dmdata))
+    if remove:
+        xml_object.remove(meta)
+    return dmdata
 
 _AttrMapBase = namedtuple('_AttrMap', 'from_xml to_xml')
 
@@ -180,8 +189,11 @@ class XmlDescriptor(XModuleDescriptor):
 
             definition_xml = cls.load_file(filepath, system.resources_fs, location)
 
+        definition_metadata = get_metadata_from_xml(definition_xml)
         cls.clean_metadata_from_xml(definition_xml)
         definition = cls.definition_from_xml(definition_xml, system)
+        if definition_metadata:
+            definition['definition_metadata'] = definition_metadata
 
         # TODO (ichuang): remove this after migration
         # for Fall 2012 LMS migration: keep filename (and unmangled filename)
@@ -236,9 +248,9 @@ class XmlDescriptor(XModuleDescriptor):
             filepath = cls._format_filepath(xml_object.tag, url_name)
             definition_xml = cls.load_file(filepath, system.resources_fs, location)
         else:
-            definition_xml = xml_object
+            definition_xml = xml_object	# this is just a pointer, not the real definition content
 
-        definition = cls.load_definition(definition_xml, system, location)
+        definition = cls.load_definition(definition_xml, system, location)	# note this removes metadata
         # VS[compat] -- make Ike's github preview links work in both old and
         # new file layouts
         if is_pointer_tag(xml_object):
@@ -246,6 +258,17 @@ class XmlDescriptor(XModuleDescriptor):
             definition['filename'] = [filepath, filepath]
 
         metadata = cls.load_metadata(definition_xml)
+
+        # move definition metadata into dict
+        dmdata = definition.get('definition_metadata','')
+        if dmdata:
+            metadata['definition_metadata_raw'] = dmdata
+            try:
+                metadata.update(json.loads(dmdata))
+            except Exception as err:
+                log.debug('Error %s in loading metadata %s' % (err,dmdata))
+                metadata['definition_metadata_err'] = str(err)
+
         return cls(
             system,
             definition,