Checks __attrs__ on session instance prior to iterating.
Add ability to pass `response` to `HTTPError()`

Just a little refactoring, but it seems nicer to me to be able to pass
the response when constructing the `HTTPError` instance instead of
constructing it and then changing the member variable.
Adds __attrs__ back to Session object
Merge pull request #1223 from andrewjesaitis/master

Fixes __getstate__ for session pickling
Merge branch 'httperror_init' of git://github.com/dmedvinsky/requests

Conflicts:
	AUTHORS.rst
	test_requests.py
Merge remote-tracking branch 'origin/master'
Fix issue #1225 (Documentation: response object status/reason)
Merge pull request #1234 from Vassius/issue-1225

Fix issue #1225 (Documentation: response object status/reason)
cleanup (remove max_retries test)
Merge pull request #1238 from oczkers/master

cleanup (remove max_retries test)
Pickling of Session and HTTPAdapter + a test

This is for issue #1088
Merge pull request #1243 from darjus-amzn/master

Pickling of Session and HTTPAdapter + a test
Fixed some pickeling issues with HTTPAdapter and Session

Added trust_env and stream to Session.__attrs__. Initialize
self._pool_connections and self._pool_maxsize in HTTPAdapter.
Merge pull request #1244 from jajadinimueter/master

Fixed further pickeling issues in Session and HTTPAdapter
Add failing test case for #1228
Use session cookies when following redirects

When a redirect was followed, only the cookies set by the initial
response were used in the follow-up request. Fixes #1228.
Do not pass cookies to resolve_redirects

SessionRedirectMixin is extending Session, so we can just use
self.cookies.
Remove duplicate comment.
Merge pull request #1245 from Damgaard/master

Remove duplicate comment.
Merge pull request #1239 from miikka/fix-issue-1228

Use session cookies when following redirects