riemann: Fix float-to-percent to not do NPEs

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
riemann: Generated events should have a default ttl

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
riemann: Use info instead of prn

Since Riemann is running in daemon mode, and logging to a file, use info
instead of prn, so we get the event printed in the log file.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
riemann: Enable logging by default

Riemann will start up even if the log directory does not exist, and an
extra warning during startup is harmless.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>