Upgraded version of sonarqube-gradle-plugin dependency to 2.8. (#879)
Upgraded version of sonarqube-gradle-plugin dependency to 2.8. (#879)

fixes TweetWallFX/TweetwallFX#878
fvogler/TweetwallFX,jmichelberger/TweetwallFX,svenreimers/TweetwallFX,reinhapa/TweetwallFX,mklaehn/TweetwallFX,TweetWallFX/TweetwallFX