Response bodies are not closed

[Phlamethrower]

Golang's http library requires you to explicitly close the response's body object in order to avoid resource leaks and to allow for connection re-use.

https://golang.org/pkg/net/http/#pkg-overview

As far as I can tell Frisby doesn't do this, which can start to cause problems if you're running large numbers of tests (running out of sockets/file descriptors, slow run time, etc).