Fix py3 issue on fernet-manage and update-endpoint

fernet-manage:
 - filter used to return a list on python2 but on python3 it returns
 an iterator which has no len method
 - Coherce the keys var into a list so we can run len on it on both
 versions

update-endpoint:
 - ConfigParser is called configparser on python3
 - try/catch and import the proper configparser

Change-Id: I8296074f4d20e47afe0c7aea41bf21999685aecd

keystone/templates/bin/_endpoint-update.py.tpl

@@ -17,7 +17,10 @@ limitations under the License.
 #!/usr/bin/env python
 import os
 import sys
-import ConfigParser
+try:
+    import ConfigParser
+except ImportError:
+    import configparser as ConfigParser
 import logging
 from sqlalchemy import create_engine
 

keystone/templates/bin/_fernet-manage.py.tpl

@@ -91,7 +91,7 @@ def read_from_files():
     for key in keys:
         with open(FERNET_DIR + key, 'r') as f:
             data[key] = f.read()
-    if len(keys):
+    if len(list(keys)):
         LOG.debug("Keys read from files: %s", keys)
     else:
         LOG.warn("No keys were read from files.")