Added drone and aircover to readme

Author: Thomas Boerger

README.md

@@ -1,7 +1,7 @@
 # Gitea SDK for Go
 
-[![Build Status](https://travis-ci.org/go-gitea/go-sdk.svg?branch=master)](https://travis-ci.org/go-gitea/go-sdk)
-[![codecov](https://codecov.io/gh/go-gitea/go-sdk/branch/master/graph/badge.svg)](https://codecov.io/gh/go-gitea/go-sdk)
+[![Build Status](http://beta.drone.io/api/badges/go-gitea/go-sdk/status.svg)](http://beta.drone.io/go-gitea/go-sdk)
+[![Coverage Status](https://aircover.co/badges/go-gitea/go-sdk/coverage.svg)](https://aircover.co/go-gitea/go-sdk)
 [![Go Report Card](https://goreportcard.com/badge/github.com/go-gitea/go-sdk)](https://goreportcard.com/report/github.com/go-gitea/go-sdk)
 [![GoDoc](https://godoc.org/github.com/go-gitea/go-sdk?status.svg)](https://godoc.org/github.com/go-gitea/go-sdk)
 [![](https://images.microbadger.com/badges/image/gitea/gitea.svg)](http://microbadger.com/images/gitea/gitea "Get your own image badge on microbadger.com")