* Add support for request.get's 'params' param
Requests defines the following API:
`get(url, params=None, **kwargs)`
* Improve typing for requests.get(params)
Add support for string form, and tighten restrictions for the dict form
to allow only string keys/vals. Technically, anything is allowed since
the code (I guess) runs `str(key)` and `str(value)`, but it seems better
to keep the stub somewhat strict so it can help pick up potential
errors.
f8717ccfc4