code: public EvacuateAction evacuate(String serverId, String host) {
          return evacuate(serverId, host, null, null);
      }
docs: Evacuates the server to a new host. The caller can supply the host name or id.
  
  @param serverId
  The server to be evacuated
  @param host
  The host name or ID of the target host (where the server is to be moved to).
  @return The action to be performed
  @see #evacuate(String, String, String, Boolean)