Fixed making redirect signature work

Author: Roland Hedberg

src/saml2/entity.py

@@ -137,7 +137,7 @@ def __init__(self, entity_type, config=None, config_file="",
         try:
             self.signkey = RSA.importKey(
                 open(self.config.getattr("key_file", ""), 'r').read())
-        except KeyError:
+        except (KeyError, TypeError):
             self.signkey = None
 
         HTTPBase.__init__(self, self.config.verify_ssl_cert,