Add no_code_generation and stop_on_failure to config

fixes issue #352

This adds the following options to `phpspec.yml'

```yaml
no_code_generation: true
stop_on_failure: true
```
I just re-factored in the process of learning to understand the code, I'm a big fan of..

* Object calisthenics
* Extract til you drop
* Leave the code you look at neater than when you arrived

and all these support neatening and tidying? Do you not agree? I can easily put it back?