Merge pull request #62 from libp2p/fix/close-canceled-dial

don't leak connections when canceling dials

limiter.go

@@ -166,5 +166,8 @@ func (dl *dialLimiter) executeDial(j *dialJob) {
 	select {
 	case j.resp <- dialResult{Conn: con, Addr: j.addr, Err: err}:
 	case <-j.ctx.Done():
+		if err == nil {
+			con.Close()
+		}
 	}
 }