In origin, get_all_endpoint_states perform all the information
formatting and returns a string.
This is not a good API approach, this patch replaces the implementation
so the API will return an array of values and the JMX will do the
formatting.
This is a better API and would make it simpler in the future to stay in
sync with origin output.
This patch is part of #508
Signed-off-by: Amnon Heiman <amnon@scylladb.com>