replace uupa-js/msgpack for msgpack package by fluentd.org
add millisecond option (issue #5)

  - if enabled (set true), the sender send logs with unix time as millisecond.
  - by default, it is not enabled.

Actually fluentd does accept seconds not milliseconds so that it is only useful when
you make a original receiver for fluentd messages.
bump version
Merge branch 'develop'