Sometime it's handy to know everything has stabilized in the cluster when we run rest tests on it. A common problem is that we run the test on varying number of nodes. This means we sometime have assigned replicas other times there is a single node and thus the replicas will stay unassigned. This means we can't use wait for green or wait for yellow.

It will be handy to add a new options to the cluster health requests allowing to wait for all shard initialization to settle down (similar to the current option to wait for all relocations to stop). The new option may even supersede the relocation option (as it is a super set).