NMS-7191: Implement "integration with OTRS-3.1+" feature

This pull request is based on branch `feature-otrs-3.1-integration-2` and the original pull request can be found here --> https://github.com/OpenNMS/opennms/pull/49

However, that pull request was not mergeable with develop.

More details can be found here:
* Jira: http://issues.opennms.org/browse/NMS-7191
* Bamboo: http://bamboo.internal.opennms.com:8085/browse/OPENNMS-NMS171
typo: should be "updated"