Add support for auth parameter

[dlopes7]

python-requests supports passing an auth object, example:

r = request(method, url, auth=("user", "password"))

It detects basic authentication and builds the Basic {b64encoded} Authentication header for you
It would be nice if mureq also supported this, to more easily replace requests in scripts that make use of auth

[slingamn]

Thanks for the suggestion. I'll consider it, but I'm thinking I probably won't do this:

1. It's fairly easy for clients to build the Authorization header themselves in this case.
2. mureq cannot support the fully general use case of the auth parameter (an arbitrarily callable that mutates the requests.Request object), since it has no analogue of the requests.Requests class.

[dlopes7]

Understandable, thanks