Upgraded version of spotbugs-gradle-plugin dependency to 1.7.1. (#736)
Upgraded version of spotbugs-gradle-plugin dependency to 1.7.1. (#736)

fixes TweetWallFX/TweetwallFX#735
svenreimers/TweetwallFX,fvogler/TweetwallFX,reinhapa/TweetwallFX,mklaehn/TweetwallFX,TweetWallFX/TweetwallFX,jmichelberger/TweetwallFX