Server Upgrade: Allow base64 encoded values

This patch allows to use base64 encoded values in update files.

Double colon ('::') must be used as separator between attribute name
and base64 encoded value.

add:attr::<base64-value>
replace:attr::<old-base64-value>::<new-base64-value>

https://fedorahosted.org/freeipa/ticket/4984

Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipaserver/install/plugins/update_passsync.py

@@ -65,7 +65,10 @@ class update_passync_privilege_update(Updater):
             root_logger.debug("PassSync user found, do update")
 
         update = {'dn': passsync_privilege_dn,
-                  'updates': ["add:member:'%s'" % passsync_dn]}
+                  'updates': [
+                      dict(action='add', attr='member', value=passsync_dn),
+                  ]
+        }
 
         sysupgrade.set_upgrade_state('winsync', 'passsync_privilege_updated', True)
         return False, [update]