Change parameter order for Stripe.request and updated all calls.

[asummers]

This allows pipelining the request body through as the first argument of Stripe.request, resulting in a cleaner request module, when used in combination in combination with handle_result.

[begedin]

@asummers Merging #197 created some conflicts. Hopefully, however, this will make the changes even simpler. Once you resolve I'll have another look and we can merge.

[coveralls]

Coverage increased (+0.4%) to 26.977% when pulling e6718d9 on asummers:change-arg-order-request into ad063a4 on code-corps:2.0.

[begedin]

This looks good. As soon as you squash, this is good to merge.