Merge pull request #143 from xiangli-cmu/master

add testandset test
feat(etcd): add listen host parameter

this separates out the listening IP from the advertised IP. This is
necessary so that we can hit etcd on 127.0.0.1 but also advertise the
right IP to the rest of the cluster.
Merge pull request #145 from philips/add-listen-host

feat(etcd): add listen host parameter