server: wait for entries to be committed in TestClusterConfigReload
server: rewrite keepSetting in TestMultiNodeKillOne

It avoids blocking http request.
server: not create new peer if exists
server: not set participant status for peer that points to itself
server: add TLSHandshakeTimeout for peer hub client
server: not add node that has been in the cluster
Merge pull request #25 from etcd-team/fix-bug

Fix bug