Fixes #327. Squashed commit of the following:

commit c2f2641e8c5fb920741f235696df58301f830926
Author: Andy Perlitch <andyperlitch@gmail.com>
Date:   Tue Nov 26 01:46:41 2013 -0800

    shortened polling time for cluster stats

commit 665cafeeadd3c6d3235894c3cb38fc2d61ed55be
Author: Andy Perlitch <andyperlitch@gmail.com>
Date:   Tue Nov 26 01:44:24 2013 -0800

    updated formatters, renamed ClusterInfo -> ClusterOverview

commit 5ffde771902dca9f7e51380d2d1b665e0bddbb0b
Author: Andy Perlitch <andyperlitch@gmail.com>
Date:   Tue Nov 26 00:31:03 2013 -0800

    added ClusterMetricsModel and ClusterInfoWidget