Braintree's sandbox no longer sending a Content-Length header

[tomheady]

In HTTP.pm, it checks for the Content-Length header to see if we have a valid response, but Braintree recently made a change in their sandbox to not send that header anymore.

Their python module checks for the length of the body instead, and the attached patch does the same (in addition to checking for the header).

https://github.com/braintree/braintree_python/blob/master/braintree/util/http.py#L80

WebService-Braintree_check_content_length.txt

[tomheady]

It looks like this was a test harness misconfiguration on our end. This is not a problem.