Bug 634126

Description of problem:
This bug appeared with introduction of unfencing generation support which was a solution of bug #622562.
It is assumed that the only symptom of this bug is mentioned problem that when fence device instance is being removed, respective "device" xml-nodes (i.e. those referencing particular fence device instance by name) are not removed from "unfence" section(s). This leads to "zombie" items.

Version-Release number of selected component (if applicable):
Any having fix for bug #622562 applied (no official one for RHEL6 presently). This solution was committed to upstream git as two subsequent commits (ca226dabc8d51073322b44971b14c3ecdc94a686 + 847508ae4483685d3eb59ed47433c02562c6bf0f).

How reproducible:
Always.

Steps to Reproduce:
1. create new fence device instance (Fence Devices tab - Add), it has to be one of the fence devices that support unfencing (see https://bugzilla.redhat.com/show_bug.cgi?id=622562#c1)
2. display details to any node of particular cluster (on Nodes tab), add a fence method, then by this method, click "Add a Fence Instance", from the drop-down menu, select a fence device instance added in step 1, then make sure the "Unfencing" checkbox is checked and confirm (optionally, check the cluster.conf on a cluster's node)
3. go back to Fence Devices tab, select fence device instance added in step 1 and delete it -- if you check cluster.conf now, you can see that respective "device" xml-nodes in "unfence" section has not been removed as expected (in "fence" section, they were removed correctly)