disallow mod of topology segment nodes

Mod of segment end will be disallowed in topology plugin.

Reasoning (by Ludwig):  if we want to properly allow mods to change
connectivity and endpoints, then we would need to check if the mod
disconnects the topology, delete existing agreements, check if the new
would be a duplicate and create new agmts. There could be some difficult
scenarios, like having
  A <--> B <--> C <--> D,
if you modify the segment B-C to A-D topology breaks and is then
reconnected.

part of: https://fedorahosted.org/freeipa/ticket/4302

Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>

VERSION

@@ -90,6 +90,5 @@ IPA_DATA_VERSION=20100614120000
 #                                                      #
 ########################################################
 IPA_API_VERSION_MAJOR=2
-IPA_API_VERSION_MINOR=129
-# Last change: pvoborni - rename topologysegment_refresh to
-# topologysegment_reinitialize
+IPA_API_VERSION_MINOR=130
+# Last change: pvoborni - disallow mod of topologysegment nodes