Added a base package for testing.

Implemented Mocker interface and MockTransport.
I'm rewriting the MockTransport, I don't think anyone requires a testing lib to do it.

``` go
type RequestRecorderTransport struct {
   Handler    http.RoundTripper
   Requests  chan *http.Request
}

func (tr *RequestRecorderTransport) RoundTrip(r *http.Request) (*http.Response, error) {
  clone := cloneReq(r)
  tr.Requests <- clone
  return tr.Hander.RoundTrip(r)
}
```