Use Logger interface instead of IO for logging

[robacarp]

First off, nice shard. I was able to get up and running quickly without issue.

While integrating this with another project, I tried to pass a Logger object in to gather the logs up with the logs from the rest of the application. Is it possible to support an external logger instance?

Thanks

[arcage]

Thank you for your valuable comment.

As you said, the external logger support seem to be better than current implement.
I will consider about it.

[arcage]

I released v0.2.4 that supports external Logger instance.

[robacarp]

@arcage wow, this looks like it will do exactly what I need. Thank you for the quick patch!