Set the out of disk node condition to unknown in the node controller if
the kubelet does not report its node condition in a long time. Update
node controller unit tests.

Implement a node condition predicate function that checks if a given
node satisfies the conditions defined by the predicate and if it
does, use that node for scheduling pods. The predicate function takes
both NodeReady and NodeOutOfDisk into consideration to determine if a
node is fit for scheduling pods.

The predicate is then passed to the node lister in the scheduler factory
so that the node lister can run the predicate function on the nodes when
schedling pods thereby omitting nodes that does not satisfy the
predicate.

Also update listers test.