Migrate to pipe. Dropped rotation options.

Fixes #28 

There are some things that may seem odd about this code, (`file` vs `directory` options) but there are plans to add the time rotation back in and I left some of the logic in there to make that easier.
I feel like the call to `unpipe` should come after the `_doRead`, otherwise aren't you effectively just throwing away data? Or is that the idea?