Created by: jwalton
Make it so we default to http.globalAgent
as the agent if no agent is explicitly specified. This is the agent that HTTP requests use by default when no agent is specified, so this is more in keeping with the http module, and it also fixes #570 (closed). :)
globalAgent
was introduced way back in node 0.5.3, so this should be a reasonably safe change as far as compatibility goes.