Display node es version in the node table

[sdesse]

It would be great if you could add the node ES version in the node table and in the disgnostic page.

It's displayed near the cluster name but some nodes can actually be in different versions.

I found that these differences can cause shard allocation issues and it's not that easy to detect a node that has the wrong version in a larger cluster.

Thanks! Sébastien

[sdesse]

I still think that a good idea, not only because it's mine :)

We've had an incident with versions mismatches and could have easily caught the problem early if this was displayed in ElasticHQ