Response with query string, but match_querystring=False should raise a warning

[rbu]

Problem

I've debugged an unrelated part of the an application for hours before noticing that mocked responses were matched unexpectedly, due to me not seeing the default match_querystring=False. A naive test case might do something like this:

$ python
Python 3.6.6 (default, Jul 19 2018, 14:25:17) 
[GCC 8.1.1 20180712 (Red Hat 8.1.1-5)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import responses
>>> import requests
>>> 
>>> responses.start()
>>> 
>>> responses.add(responses.GET, "https://example.com/api?endpoint=1",
...     json={'endpoint': 1}
... )
>>> responses.add(responses.GET, "https://example.com/api?endpoint=2",
...     json={'endpoint': 2}
... )
>>> 
>>> requests.get('https://example.com/api?endpoint=2').content
b'{"endpoint": 1}'
>>> requests.get('https://example.com/api?endpoint=1').content
b'{"endpoint": 2}'
>>> 

Proposal

While I'd prefer the default for match_querystring to be changed, I'd propose responses throws a RuntimeWarning when a response is added that contains a query string without setting match_querystring explicitly.

[rbu]

Another example of someone stumbling over this is #203

[dcramer]

Not opposed to that. I'd also be fine just changing match_querystring=True (implicit only) when you pass a URL with a querystring.

[rbu]

@dcramer I like the idea of a giving match_querystring a new default value that depends on the url. Is this something you'd be working on? If not, I'd look into submitting a PR for this next week.

[dcramer]

I probably won’t have time, but if you throw up a PR I’m happy to review/merge

[rbu]

@dcramer I have added a pull request for the automatic behavior you proposed in #213.
I'd very much appreciate your review.