Small changes to API - RequestResponse.Headers is now Header, to match the
type.  Get rid of Method type, was kinda pointless.  New Params
map[string]string type for easier typing.  Now pays attention
to RequestResponse.Headers, which was previously ignored.
Table driven testing!  Only testing requests in this commit, still need to add response tests.
go get github.com/jmcvetta/randutil
update readme
test correct request method
add note
Merge branch 'table_driven_tests'