Support ignoring certain keys in predicateGenerators

[bbyars]

Let's say you had a proxy listening on port 3000 configured like this:

{
  "to": "http://origin-server.com",
  "predicateGenerators": [{
    "matches": { "query": true },
    "ignore": { "query": "startDate" }
  ]}
}

Then we get a request:

http://localhost:3000/path?limit=100&enhanced=true&startDate=2017-09-07&endDate=2017-10-11

The saved predicate should not have the startDate key.

Requested by Sabari Karthik.

[gePower]

Hi, can you assign me to the issue?

[bbyars]

Done!

[gePower]

thanks ! it's already done ! https://github.com/bbyars/mountebank/pull/661