Resolve issues from multi-server patch

[tractorcow]

Placeholder issue to ensure feedback from #60 doesn't get lost.

In #60 when doing a multi-server deployment, output logging is no longer streamed, but is consumed from each node before being merged and output. When operating in single-server mode, this isn't necessary, and streaming should be re-enabled.

Also need to update symfony dependencies (2.x is super outdated).