Update drone domain

README.md

@@ -1,5 +1,5 @@
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0) [![GoDoc](https://godoc.org/github.com/cs3org/reva?status.svg)](https://godoc.org/github.com/cs3org/reva)
- [![Gitter chat](https://badges.gitter.im/cs3org/reva.svg)](https://gitter.im/cs3org/reva) [![Build Status](https://cloud.drone.io/api/badges/cs3org/reva/status.svg)](https://cloud.drone.io/cs3org/reva)
+ [![Gitter chat](https://badges.gitter.im/cs3org/reva.svg)](https://gitter.im/cs3org/reva) [![Build Status](https://drone.cernbox.cern.ch/api/badges/cs3org/reva/status.svg)](https://drone.cernbox.cern.ch/cs3org/reva)
  [![Go Report Card](https://goreportcard.com/badge/github.com/cs3org/reva)](https://goreportcard.com/report/github.com/cs3org/reva)  [![codecov](https://codecov.io/gh/cs3org/reva/branch/master/graph/badge.svg)](https://codecov.io/gh/cs3org/reva) [![FOSSA Status](https://app.fossa.com/api/projects/custom%2B11650%2Fcs3org%2Freva.svg?type=shield)](https://app.fossa.com/projects/custom%2B11650%2Fcs3org%2Freva?ref=badge_shield)
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