Value of etcd instance lock could be more informative

[przemyslaw-dobrowolski-cl]

During the process of master server selection, each gohan server performs a CAS operation in etcd in order to lock itself as a leader. The key is a constant path for all servers but the value is composed of the server host name and an randomly chosen UUID. This could be improved for the purpose of tracking down which Gohan server is the current leader. Using an IP address instead of the host name (or using both of these) would be more informative as the hostname does not need to be unique nor informative nor easy to dns-reverse in a local network.