Update maven-release-plugin

We should update maven-release-plugin to version 2.5 (tested and worked well) as we had issues with 2.3.1 in the past. We need to update the parent pom, release it and use it for the module archetype.

See https://github.com/openmrs/openmrs-contrib-maven-parent-module/blob/master/pom.xml#L325