BUG-732 Add rollback-on-error error-option to edit-config rpcs from netconf-connector

Just in case rollback-on-error capability is supported

+ Add error response warning to netconf-connector

Change-Id: I16251a12b270bd0ed89b39bfccc5251b4b3fe934
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>