Revert "Try speeding up travis by only running one JDK, one platform."

This reverts commit 8ddeaafec725d650688c019b10644b86c00dd8b6.
Use container-based infrastructure to speed up
Skip installing Java 8 with sudo
Merge pull request #2317 from jruby/ha-feature-sudo-false

Move to container-based infrastructure and cache maven artifacts