Force log entries to be one line

Different versions of syslog-ng and probably other syslog services
handle multi line log messages differently and sometimes quite
poorly. This patch collapses multi line log messages into single
lines before sending them on to syslog.

It's just a copy of what was already in Python's logging.Formatter
but altered to replace the newlines with #012. I used #012 since
that's a convention we've already used elsewhere in Swift.

Change-Id: I8d0509b7cf48e45c2cf6480b51c67eec5bc94fe2
Merge "Force log entries to be one line"