fixes https://github.com/kennethreitz/requests/issues/1359
which has not yet been released

Also put out the speed hack from the core code.

It is assumed when arguments and config parameters are merged.
Otherwise, it is not possible to set this option from the .cfg.

Allows easier hack.

This reverts commit 7fe0677c.

This reverts commit 580ab267.

This reverts commit 0c552d82.

This reverts commit 06ebfdb7.

This reverts commit 7581e55e.

This reverts commit 4e428fdc.