Adapted sip_subscribe_presence.py to the new Credentials class

darcs-hash:20090518141139-58103-94714efe3d2a0db5433be3497c4cd3b81ed3e35a
Adapted sip_subscribe_rls.py to the new Credentials class

darcs-hash:20090518141208-58103-6aefde3721f9a2cfbc68bf2bffe9427d72011926