forgetsy v 0.1

pinging @fancyremarker and @dblock for review.

This is a first round implementation of forgetsy. Please read the [README](https://github.com/cavvia/forgetsy/tree/dev) to familiarise yourself with the aim of the library.

It should be considered unstable at this stage. There are still a few optimisations required before I would use this in production too.