Add unit tests

As discussed on IRC, here are some tests written with atoum. 
I will continue to cover Pickle source code.

Build status: [![Build Status](https://travis-ci.org/jubianchi/pickle.svg?branch=atoum-tests)](https://travis-ci.org/jubianchi/pickle)
@jubianchi 2 of these bin scripts will be part of the files being worked on, while the others are third-party. This can be confusing IMO.

The pickle bins are not scripts you will use when working on the project. they are scripts you will develop