allow calling httpLog with IncomingMessage obtained from HttpClient
fix arguer (depends on PR to arguer for multi-mutex support)
fix error in httpLog ctor and add test for constructing with IncomingMessage
Merge branch 'master' into response-ctor
add docs to README re: http.IncomingMessage constructor
Merge pull request #3 from bretcope/response-ctor

allow calling httpLog with IncomingMessage obtained from HttpClient