fix criterions once more

* Fix handling of both missing and null/None values for includes / excludes
* Handle criterions without values

resources/lib/criterion_parser.py

@@ -20,18 +20,18 @@ def parse_criterion(criterion):
 
     value = criterion.get('value', '')
     if isinstance(value, dict) and 'depth' in value:
-        if 'items' in value and value['items'] is not None:
+        if value.get('items') is not None:
             filter['value'] = list(map(lambda v: v['id'], value['items']))
 
-        if 'excluded' in value:
+        if value.get('excluded'):
             filter['excludes'] = list(map(lambda v: v['id'], value['excluded']))
 
         filter['depth'] = value['depth']
     elif isinstance(value, dict) and not value.keys() - ['value', 'value2']:
         filter.update(value)
     elif isinstance(value, list):
         filter['value'] = list(map(lambda v: v['id'], value))
-    elif value is not '':
+    elif 'value' in criterion:
         filter['value'] = value
 
     return filter