Response Validation & Processing

- [x] Add Response Precondition checking
- [x] Add Response signature verification
- [ ] Add Response Validation
- [ ] Add Response Assertion Validation
- [ ] Add Response Assertion Transformers
- [ ] Test all the things
Old docblock that has not been updated yet ;) 

FYI: The architecture still is a bit a moving target seeing I uncover more and more hidden functionality as I go. The idea is to end up with a pipeline with different stages (precondition, check signature, check assertions, transform assertions) that each have a distinct task and can exit the pipeline on {failure-condition}.