Switch from Oracle Java 8 to OpenJDK

[netsensei]

The PPA that is used to install Oracle Java 8 has been deprecated following a further closing down of the proprietary ecosystem by Oracle. As such, we are forced to abandon Oracle Java 8 support and move to OpenJDK.

http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html

Java is needed for Apache Solr which is the backend for Project Blacklight. Apache Solr 7 and up work just fine with OpenJDK.

Tasks

• Yank out the PPA reference in the datahub.yml playbook
• Add the geerlingguy.java Ansible role