ubuntu config: use V1 Format

with `--use-v1-config`, it can use emmbedded Ruby code.
ref: http://docs.fluentd.org/articles/config-file#v1-format

This feature can use fluentd v0.10.46 or later.
ref: https://groups.google.com/forum/#!msg/fluentd/ymqI5OKV1Js/QMS8HT30wGMJ