Requests support

Hi,

as discussed before. Note that I've created a new SSL certificate because requests verifies the host name by default (otherwise a whole aspect of HTTPS is undermined). The certificate included is valid for 'localhost'.

I've also included tests for redirection (forgot to mention in the commit message).

These changesets pass pep8, small and medium tests on my machine.
Finally, this is just for me and my understanding: what brings using a context with a threadpoolexecutor? (meaning: is there any cleaning that I missed in the previous version?), or is it just for visual idententation (which is great btw)?