Check script

The script scans all the indexes and checks if they are in a sane state:
* Exist
* Open
* Right number of shards
* Right number of replicas
* All replicas assigned

It collects all the errors and spits them out at the end.

It can run in "nagios" mode where it'll look like a nagios plugin.

Change-Id: Ic496b903fb9911c6ae6983d2b301aa4969a06e23