Use user supplied options when resending authenticated requests

Hooks sometimes have to send requests (e.g. when responding to a 401 during
authentication).

All keyword arguments should be passed along when hooks are dispatched so that
if a user wanted to use a timeout, stream, specify a cert location with the
verify flag, etc, their specification can be followed.
Adding test to ensure options like stream function with authentication

This test demonstrates the reason why we need to pass kwargs to hooks. Without
it, features like stream cannot work with authentication.
New tests fail on python 3.x because read() returns bytes and the test checks for strings
Allow RequestsCookieJar to be updated with cookies from a CookieJar
Fixing test for python3
Remove ability to from RequestCookieJar __getitem__, __setitem__ to use cookies as keys
Merge pull request #1194 from gazpachoking/cookiejar_update

Allow RequestsCookieJar to be updated with cookies from a CookieJar
use explicit scheme for proxies in the docs

Issue #1192 tried to force user to provide a scheme for proxy urls.
As this would break backwards compability change the docs instead.
Make sure session cookies do not overwrite explicit request cookies
Implement RequestsCookieJar.copy
Use RequestsCookieJar.update when merging cookiejars
Rethrow underlying exceptions.
Merge pull request #1199 from t-8ch/docs_explicit_proxy_scheme

Use explicit scheme for proxies in the docs
Merge pull request #1200 from gazpachoking/session_cookies_fix

Make sure session cookies do not overwrite explicit request cookies
Merge pull request #1193 from Lukasa/timeout_exception

Throw more informative exceptions.
Lukasa is lazy
Missing line was allowing redirects with HEAD

Closes #1203
Unquote proxy usernames and passwords.
Revert "Lukasa is lazy"

This reverts commit 178ff62b934c30278114028f654e42374206c291.
Merge pull request #1210 from Lukasa/urlencode_proxy

Unquote proxy usernames and passwords.
Merge pull request #1205 from sigmavirus24/fix1203

Missing line was allowing redirects with HEAD
Revert "If Content-Length is already set.."[1]

This reverts commit 544d08d0f61c35358cf13b4a6b677e4e51dbbe7e.

[1]"If Content-Length is already set, don't over ride it"