Fix/upgrade TravisCI to trusty (#309)
Fix/upgrade TravisCI to trusty (#309)

* updated matrix configurations to manually install non-supported java versions

* fix oraclejdk7 typo in travisci

* removed oraclejdk7 since default support does not work

* travisci review: removed java6 and added explicit dist (trusty)

asciidoctor/asciidoctor-maven-plugin,abelsromero/asciidoctor-maven-plugin,abelsromero/asciidoctor-maven-plugin,asciidoctor/asciidoctor-maven-plugin,abelsromero/asciidoctor-maven-plugin,asciidoctor/asciidoctor-maven-plugin