salt.utils.http.query results not consistent across backends.

Description of Issue/Question

salt.utils.http.query result ouput not consistent across backends.

The following is inside salt.utils.http.query

    if not backend:
        backend = opts.get('backend', 'tornado')

salt.utils.http.query returns a dict. This dict always contains handle. However handle can be:

• requests.models.Response from requests.Session()
• tornado.httpclient.HTTPResponse from tornado

It appears backend set to urllib2 may not work.

salt.utils.http.query should return a consistent result. e.g.

{
response_headers: [list in order received]
response_status: <User friendly message>
body: <response>
size: <int>
Optionally consider some of the standard response hearders like Etag, Last-Modified, Data, Content-Type, Content-Length, Expires, Host, Cache-Control
}

Setup

Steps to Reproduce Issue

Change backend and run the test suite. Or use fileclient.get_url()

Versions Report

Development, 2018.X 2017.X

Start with salt.utils.http.query and reproduce the issue by changing the backend, then inspect the results from fileclient.get_url() and the test suite. Compare the returned values across the requests, tornado, and urllib2 paths; done means the backends expose a consistent result and the relevant tests pass.