Fix dump_cib method for corosync service provider

Corosync_service.rb is missing block_until_ready() call
in its dump_cib method. That might result in empty xml result.

Closes-bug: #1355816

Change-Id: I757522b297e0025cee7de3130743e0ef6a6fb77b
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Fix dump_cib method for corosync service provider" into stable/5.0