chore: travis-ci config and gradle 3.4.1#6

tompluess wants to merge 2 commits intoratpack:masterratpack/example-ratpack-gradle-java-app:masterfrom

tompluess:chore/gradle-3.4.1tompluess/example-ratpack-gradle-java-app:chore/gradle-3.4.1Copy head branch name to clipboard