dodo: update travis config to use trust dist, update scala/jdk
dodo: update travis config to use trust dist, update scala/jdk

Problem

The dodo .travis.yml configuration is using the default travis
build image, which has been moved to dist: xenial and does
not have the oraclejdk8 available.

Solution

Explicitly list dist: trusty, as the other Twitter ecosystem projects
do. Modify the Scala version to match our other projects. Move
all projects to `openjdk8`.

Result

Dodo build should pass.

JIRA Issues: CSL-8640

Differential Revision: https://phabricator.twitter.biz/D362555

twitter/finatra,twitter/finatra,twitter/finatra