ProcessStatementAdd chains to RequirementApprove when the requirement is satisfied

The goal is to avoid code redundancy, to increase
serializability/logging and to use what ops are made for

process/ops.py

@@ -373,17 +373,17 @@ class ProcessStatementAdd(op.Operation):
                 robot = bmodels.Person.objects.get(email="nm@debian.org")
             except bmodels.Person.DoesNotExist:
                 robot = self.audit_author
-            self.requirement.approved_by = robot
-            self.requirement.approved_time = self.audit_time
+            req_approval = RequirementApprove(
+                requirement=self.requirement,
+                audit_author=robot,
+                audit_notes="New statement received, the requirement seems satisfied",
+                audit_time=self.audit_time,
+            )
+            req_approval.execute()
         else:
             self.requirement.approved_by = None
             self.requirement.approved_time = None
-        self.requirement.save()
-
-        if self.requirement.approved_by:
-            self.requirement.add_log(self.requirement.approved_by,
-                                     "New statement received, the requirement seems satisfied",
-                                     True, action="req_approve", logdate=self.audit_time)
+            self.requirement.save()
 
     def notify(self, request=None):
         if self.requirement.type not in ("intent", "advocate", "am_ok"):