enhancement = add option to save/record http errors.

[johndpope-karhoo]

  I'm using this library in conjunction with ohttpstubs 

Was using the SWHttpTrafficRecorder recorder to audit the traffic - while it may seem not worthwhile - I've since added a new stub to reflect error codes returned from server.

let notConnectedError = NSError(domain:NSURLErrorDomain, code:62), userInfo:["NSLocalizedDescription":"Error getting Trip"] )
return OHHTTPStubsResponse(error:notConnectedError)

[johndpope-karhoo]

eventually when it is ready to be consumed it would be glued into something like this
AliSoftware/OHHTTPStubs#214