allow custom headers to be provided
use HTTP::Response and HTTP::Request's built in as_string() for logging
v0.0200
Merge pull request #4 from ironcamel/custom-headers

allow custom headers to be provided
require HTTP::Response::Stringable v0.0002
allow headers as hashref or arrayref
don't squash custom Content-Type header if it is passed in
v0.0201
better logging and require latest HTTP::Message
v0.0202
added WebService::Stripe to examples