Fix http client timeout (#248)

* fix http client timeout, and test span counter

* bump version to 0.4.1

* revert span counter

* revert version change

Author: tonyredondo

agent/recorder.go

@@ -80,7 +80,7 @@ func NewSpanRecorder(agent *Agent) *SpanRecorder {
 	r.cache = agent.cache
 	r.flushFrequency = agent.flushFrequency
 	r.url = agent.getUrl("api/agent/ingest")
-	r.client = &http.Client{}
+	r.client = &http.Client{Timeout: 60 * time.Second}
 	r.stats = &RecorderStats{}
 	r.t.Go(r.loop)
 	return r