Merge tag '3.1.3' into develop

Rel

* tag '3.1.3':
  [maven-release-plugin] prepare for next development iteration
  [maven-release-plugin] prepare release halbuilder-core-3.1.3
Changes to support optionally always having embeded resources rendered as a JSON array even when there is only one. Requires changes to halbuilder- api, core, and json which were also forked for this change.