Python 3.2 workaround: Drop usage of enum module

enum is not yet available in Python 3.2, but as long as snakefruit still runs
Ubuntu 12.04 we need to get along without it.

britney.py

@@ -1755,9 +1755,9 @@ class Britney(object):
         for policy in self.policies:
             if suite in policy.applicable_suites:
                 v = policy.apply_policy(policy_info, suite, src, source_t, source_u, excuse)
-                if v.value > policy_verdict.value:
+                if v > policy_verdict:
                     policy_verdict = v
-                    if policy_verdict.is_rejected:
+                    if policy_verdict in [PolicyVerdict.REJECTED_PERMANENTLY, PolicyVerdict.REJECTED_TEMPORARILY]:
                         excuse.is_valid = False
 
         if suite in ('pu', 'tpu') and source_t:

policies/policy.py

@@ -1,5 +1,4 @@
 from abc import abstractmethod
-from enum import Enum, unique
 import apt_pkg
 import os
 import time
@@ -9,8 +8,7 @@ from hints import Hint, split_into_one_hint_per_package
 from britney_util import ensuredir
 
 
-@unique
+class PolicyVerdict:
-class PolicyVerdict(Enum):
     """"""
     """
     The migration item passed the policy.