Added chaos experiments

[Geertvdc]

Added new functionality to perform chaos engineering like experiments on the mocks by adding Prefer headers.

You can send different status code or add latency to the response by adding the statusCode and/or latency parameters inside the prefer header. Using the statusCodeRate and latencyRate parameters you can specify when to add these behaviours. Use a value between 0 and 100 (%) to add less or more randomness.

An example:

GET http://localhost:5001/v1/pets/1
Prefer: statusCode=500, statusCodeRate=50
Prefer: latency=500, latencyRate=50

Pair programmed with @mivano, @NielsNijveldt, @dtiemstra

[Geertvdc]

@jormaechea is this something you could review?

[jormaechea]

@Geertvdc thanks for the PR. It looks like a really good idea. Sadly I'm traveling without access to my computer so I won't be able to review this at least until end of March.

I’ll let you know as soon as I can take a look at it.