Add support for URL parameters

[domdom82]

It maybe tedious to upload an entire config.yml just to change a single endpoint.
A good example might be a /slow endpoint:
It usually waits for a defined time and then responds back to the client.

Now instead of testing various config.yml every time we want to make a change in the slowness, we could allow endpoint parameters to be overridden via URL parameters.

E.g.

GET /slow?delay=5s

this would overwrite the config.yml entry:

servers:
  - http:
      port: 8080
      responses:
        /slow:
          get:
            static:
              - status: 200
                body: this is a slow response
                delay: 500ms  << here

Things to consider:

• Be vary of sequences and loops.
• If we want to support that full circle, this means if you want to change the delay of the 3rd response in a sequence you have to do 2 GETs without the parameter, then one GET with the parameter