LOGSTASH-1201 - Java7/NIO.2 File Input Plugin

Hastily written, barely tested, apparently working.

Submitted for your review & comment.

I expect it will need a feature or two added before it's ready to merge.  But right now I just want some feedback on this sketch of a plugin.  I'll clean up the formatting, indentation, etc, dont worry about that.  How bad is my jruby?

Thanks!!!