Determine index mismatch in cluster and warn on cluster info page

The indexes on the nodes of the extranet cluster are currently out of sync, but there's no easy way to work this out.

For each node on the cluster information page, add a line which lists the number of documents in the index. The code to do this on each node is found in indexbrowser.jsp, and needs to be added to the status object which is retrieved from each node by the cluster status action.

At the top of the page, add a line called 'Index status', which displays a green 'OK' if the number of documents on all nodes match, or a red 'OUT OF SYNC - REQUIRES REINDEX' if the number of documents differ.