Changed the type of the reader config data.

* Now it also contains how many errors to each before dying.
* Also added a data type to track the errors being accumulated.
* Lenses for everyone!
Added an error accumulator.

* Collapsed RetryT into GithubInteractionT.
* Made GithubInteractionT wrap RWST.
* Added more primitives to compose these computations.
v0.4.0.0