feature for management - add wild card to show state of all rivers

[Chadwiki]

As of now you have to know the river name for the remote config to get its status. I would like to request to use a wild card on the status.
This could be extended to all other commands ( stop, restart, fullupdate, incrementalupdate)

currently you use to see all rivers:
curl -XGET localhost:9200/_remote_river/list
then
curl -XGET localhost:9200/_river/my_remote_river/_mgm_rr/state

Propose:
curl -XGET localhost:9200/_river/*/_mgm_rr/state