4.28

Issue #259: update to CS 8.28
Issue #232: update to SQ 7.9
update to JDK 11

Issue #278: disable inspection that suggest to convert block to expression
Issue #274: update forbiddenapis
Issue #269: update pom.xml to include test sources for checkstyle
Issue #269: enable checkstyle for test sources
Issue #270: send jacoco coverage to sonarqube
Issue #262: use wercker for Sonarqube.io validation in PRs
Issue #261: let Travis avoid building branches in repo other then master