Compensation index view

* adds filters and table optimizations for compensation index rendering
* fixes recorded_by/checked_by confusion in intervention table

intervention/models.py

@@ -56,6 +56,9 @@ class Intervention(BaseObject):
     # Users having access on this object
     users = models.ManyToManyField(User)
 
+    def __str__(self):
+        return "{} ({})".format(self.identifier, self.title)
+
     def delete(self, *args, **kwargs):
         """ Custom delete functionality