Make KelasticMulti sort aggregated responses for multiple indexes

[michaelgibson]

The previous KelasticMulti was sorting the response for each index individually, then append the presorted result into the response.
It was also only retrieving a increasingly smaller subset of any subsequent index in an attempt to fit something from all indexes on one page.
This ends up displaying mixed results that are not necessarily ordered by time.

The solution was to get the full target size resultset for each index(50), append them into a single array and then sort.

Pretty much re-did KelasticMulti. Please review thoroughly before merging. :)

[rtoma]

I have merged this pull request in a private fork. It works great!

In my setup I have logstash process multiple types, all writing to their own elasticsearch index.

Before the apply my events from multiple types were grouped by type and sorted by timestamp. Very annoying if you want to correlate an issue using multiple (log)types.

With this PR I now see events sorted by timestamp, no matter what type they are.

Thanks!

p.s. why is this excellent PR waiting 8 months now for merge? Is Kibana2 end of life?