Update hacking for Python3

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

Fix problems found.

Remove hacking and friends from lower-constraints, they are not needed
for installation.

Change-Id: I5ae47a7b11ff29a301e440c15daf30db7738485b

glanceclient/common/http.py

@@ -177,7 +177,7 @@ class HTTPClient(_BaseHTTPClient):
             if kwargs.get('insecure', False) is True:
                 self.session.verify = False
             else:
-                if kwargs.get('cacert', None) is not '':
+                if kwargs.get('cacert', None) != '':
                     self.session.verify = kwargs.get('cacert', True)
 
             self.session.cert = (kwargs.get('cert_file'),