Squashed commit of the following:

commit f7005db5868f9aa5f9b07f0e8e3135d2c672a764
Author: Albert Louis Rossi <arossi@otfrid.fnal.gov>
Date:   Thu Apr 4 08:59:51 2013 -0500

    module: webadmin (pool-queue-plots)

    On start-up it is possible for the PoolMonitorCollector to retrieve a CostModule with NULL CostInfo objects for the pools.

    There is currently a bug in the RrdPoolInfoAgent's handling of this code branch which causes an NPE; this is because the
    "addAll" method is given a placeholder replacement for the NULL CostInfo object which does not have any of the required
    PoolQueueInfo attributes set.

    The correct procedure here is to skip the update rather than force it to 0.

    Acked-by:
    Target: trunk
    Require-book: no
    Require-notes: yes

    RELEASE NOTES:
    Under certain conditions it is possible to get a NPE at startup of the webadmin pages when pool-queue-plotting is enbaled.  This has been fixed.