Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

Fix problems found.

Update local hacking checks for new flake8.

Remove hacking and friends from lower-constraints, they are not needed
to be installed at run-time.

Change-Id: Ia6af344ec8441dc98a0820176373dcff3a8c80d5

watcher/applier/actions/base.py

@@ -140,7 +140,7 @@ class BaseAction(loadable.Loadable):
         raise NotImplementedError()
 
     def check_abort(self):
-        if self.__class__.__name__ is 'Migrate':
+        if self.__class__.__name__ == 'Migrate':
             if self.migration_type == self.LIVE_MIGRATION:
                 return True
             else:

watcher/applier/actions/resize.py

@@ -47,24 +47,24 @@ class Resize(base.BaseAction):
 
     @property
     def schema(self):
-            return {
-                'type': 'object',
-                'properties': {
-                    'resource_id': {
-                        'type': 'string',
-                        'minlength': 1,
-                        'pattern': ('^([a-fA-F0-9]){8}-([a-fA-F0-9]){4}-'
-                                    '([a-fA-F0-9]){4}-([a-fA-F0-9]){4}-'
-                                    '([a-fA-F0-9]){12}$')
-                    },
-                    'flavor': {
-                        'type': 'string',
-                        'minlength': 1,
-                    },
+        return {
+            'type': 'object',
+            'properties': {
+                'resource_id': {
+                    'type': 'string',
+                    'minlength': 1,
+                    'pattern': ('^([a-fA-F0-9]){8}-([a-fA-F0-9]){4}-'
+                                '([a-fA-F0-9]){4}-([a-fA-F0-9]){4}-'
+                                '([a-fA-F0-9]){12}$')
                 },
-                'required': ['resource_id', 'flavor'],
-                'additionalProperties': False,
-            }
+                'flavor': {
+                    'type': 'string',
+                    'minlength': 1,
+                },
+            },
+            'required': ['resource_id', 'flavor'],
+            'additionalProperties': False,
+        }
 
     @property
     def instance_uuid(self):

watcher/applier/workflow_engine/default.py

@@ -112,7 +112,7 @@ class DefaultWorkFlowEngine(base.BaseWorkFlowEngine):
 
             return flow
 
-        except exception.ActionPlanCancelled as e:
+        except exception.ActionPlanCancelled:
             raise
 
         except tf_exception.WrappedFailure as e: