Add support for the verify_ssl, ca_certs and timeout parameters for the ...

...request transport.

Fix for issue #463.
I dont recall what the default transport does, but ideally it would match that API.

Basically we don't care about the Requests API, we just want transports to be as interoperable as much as possible.

In all honesty, the requests transport isn't even useful these days outside of the fact that I believe it handles SNI and we don't. If thats easy to add to the default HTTP transport I'd happily axe this one.