Description of problem:

Set up a cluster using fencipmilan method and the cluster nodes's fencing schema
does not allow for the "lanplus" parameter which is added (possibly used,
possibly not.. i don't know)

Add the optional attribute in the schema file ...

        <!-- ILO, ipmilan -->
        <group>
         <optional>
          <empty/>
         </optional>
         <optional>
          <attribute name="option"/>
         </optional>
         <optional>
          <attribute name="lanplus"/>
         </optional>

for lanplus, and the sys-conf-cluster seems to work fine.


Version-Release number of selected component (if applicable):

system-config-cluster-1.0-45.1.0


How reproducible:

Pretty much every time.

Steps to Reproduce:
1. Use the attach cluster.conf (created by sys-config-cluster
2. open it up in system-config-cluster
3. see xmlint error messages for invalid attributes in xml file.
  
Actual results:

User can continue, but having to click this is a pita after editing the file or
ignoring it.

Expected results:

xml created by tool to validate.

Additional info:

Fixed cluster.ng and the cluster.conf in question to be attached.