Push all available logs on container start

[GuiSim]

Could it be possible to go "back in time" when the logmatic-docker is started to grab all logs from currently running containers?

This would make it harder to lose logs and would eliminate potential issues when a new machine is started and it contains multiple docker containers. The logmatic-docker container might not be up fast enough to grab all logs from other containers.

Example:

1. Container A starts and logs something.
2. logmatic-docker container is started
3. Logs from container A that were made at boot time are lost. New logs are correctly captured.

[GuiSim]

This should be possible using GET /containers/{id}/logs

It also supports the ?since parameter which allows you to set the timestamp to use.