host: Always use logfmt output when logging
host: Always use logfmt output when logging

When run as an Upstart job, stdout is connected to a pty which
ultimately gets logged to a file, which means color codes and escape
characters end up being logged to the file.

Signed-off-by: Lewis Marshall <748e1641a368164906d4a0c0e3965345453dcc93@lmars.net>

philiplb/flynn,flynn/flynn,lmars/flynn,lmars/flynn,benbjohnson/flynn,flynn/flynn,benbjohnson/flynn,philiplb/flynn,philiplb/flynn,benbjohnson/flynn,philiplb/flynn,flynn/flynn,flynn/flynn,benbjohnson/flynn,flynn/flynn,benbjohnson/flynn,lmars/flynn,benbjohnson/flynn,philiplb/flynn,lmars/flynn,lmars/flynn