New plugin logstash-input-mongodb

I've create an input plugin for mongodb and would like to contribute it to the plugin repository. It currently fits my needs and I'm working with a couple of interested parties that found my plugin on github to make it usable for them and ideally anyone else that would want to move log data, or any data from mongodb through logstash.

I'd like for it to be reviewed in it's current state and to gather input. I will begin to write tests for it shortly. Also, I'm curious about the use of JRuby which the jdbc/sqlite3 gem requires. Does logstash always run on JRuby or should I bother making this run in any ruby?

Repo: https://github.com/phutchins/logstash-input-mongodb