Update the HISTORY for v1.2
Add correct defaults in Session.send()

Resolves #1258

Also fixed the tests to reflect the necessary changes.
This should take care of #1266

We were sending 'None' as the Content-Length on requests where the body was a
generator. This commit should prevent that entirely.
Finally resolve #1084

Send body on redirect when POSTing or PUTing.
Restore Session.request docstring

Resolves #1251
Fix the tests and unseparate comments from code

See the comments on the previous few commits on GitHub.
Use session defaults instead of arbitrary ones
Merge pull request #1267 from sigmavirus24/master

One last pull request before 1.2 ideally