build.gradle: Bump jacoco to 0.8.1 and coveralls-gradle-plugin to 2.8.2
build.gradle: Bump jacoco to 0.8.1 and coveralls-gradle-plugin to 2.8.2

igniterealtime/jxmpp,Flowdalic/jxmpp,igniterealtime/jxmpp,Flowdalic/jxmpp,igniterealtime/jxmpp,Flowdalic/jxmpp