This should make them easier to read and adds them to the test suite
I changed the example from a two node cluster to a single node cluster
because that is what we have running in the integration tests. It is also
what a user just starting out is likely to see so I think that is ok.
The number of current pending tasks is useful to detect and overloaded master. This commit adds it to the cluster health API. The complete list can be retrieved from the dedicated pending tasks API.
It also adds rest tests for the cluster health variants.
Closes#9877
The description of the timeout parameter was worded misleadingly; it implied that the API would wait until the cluster reached the desired level and then stayed at that level for the timeout. I've tweaked the sentence to remove the risk of confusion.