Added new monitors for watching number of instances get to a certain count using polling.
Added new commands to sample client which give some statistics.
Added the ability to kill and restart specific instances.
Fixed incorrect documentation on using-the-sample-client.
Added helper functions under the response package to extract fields from
aurora.Response.
Some tests included for making sure the JSON blob pulled from Zookeeper
is correct.
Updated client to be able to take Zookeeper json cluster config that is
currently being used in aurora (clusters.json usually located at
/etc/aurora/cluster.json).
Changed error messages to no longer have a period at the end as that was
throwing off printing of the error.
Modified samuel's ZK library slightly to stop verbose logging using a
NoOpLogger from stackoverflow.
