add elasticsearch plugins

[jfroche]

Add some elasticsearch plugins

[bfirsh]

What do these plugins do? Are they essential?

It might be interesting to make this configurable somehow.

[jfroche]

these plugins enable you to explore content through web interface. They are not essential but really useful when you want an easy way to explore content indexed in ES (cf http://mobz.github.io/elasticsearch-head/ )

[hacfi]

I also consider mobz/elasticsearch-head a must-have. The other one I haven’t tried yet.