Add Quality gate badge to README

README.md

-SonarQube [![Build Status](https://travis-ci.org/SonarSource/sonarqube.svg?branch=master)](https://travis-ci.org/SonarSource/sonarqube)
+SonarQube [![Build Status](https://travis-ci.org/SonarSource/sonarqube.svg?branch=master)](https://travis-ci.org/SonarSource/sonarqube) [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=org.sonarsource.sonarqube%3Asonarqube&metric=alert_status)](https://sonarcloud.io/dashboard?id=org.sonarsource.sonarqube%3Asonarqube)
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 Continuous Inspection