[xcuActor] Handle multi-line responses to raw device commands

This issue was initially filed into JIRA by 'cloomis' at 17/Mar/16 3:05 PM as ICS-28.

Some devices can return multiple responses to a single command, but without any final delimiter. Notably the Sunpower controller, grr.

I suggest added a timeout argument to the "raw" command(s), where the actor will continue to fetch data until the device has been silent for that long. There could be other schemes, but this seems general and sufficient.