Update dependencies.

From
 [![Dependency Status](https://david-dm.org/cgiffard/Behaviour-Assertion-Sheets.png)](https://david-dm.org/cgiffard/Behaviour-Assertion-Sheets)
To
 [![Dependency Status](https://david-dm.org/timoxley/Behaviour-Assertion-Sheets.png)](https://david-dm.org/timoxley/Behaviour-Assertion-Sheets)