#1631 log: add support for "cloud resilience" feature

[Vu Minh Nguyen]

This ticket make the LOG service be able to handle the case that both SC nodes are down at the same time meaning that no log server is running (server down).

When one or both nodes go up again the log service must be able to resume its work preferably without actions by the clients. A log client should not have to be aware of if one or both SC nodes are down. The only thing that should happen is that a TRY AGAIN (and in some cases TIMEOUT) reply is received which is the behavior of the current log service if a request cannot be handled for the moment.

It is the responsibility of the client to decide how to handle this. A recommended way is to try the same request again for a limited time or a limited number of retries with a delay in between.

[Vu Minh Nguyen]

Duplicated. Refer to [#1179]