Updated deps for latest git, using released guava 15
[maven-release-plugin] prepare release halbuilder-core-3.1.1
[maven-release-plugin] prepare for next development iteration
Merge branch 'release/3.1.1'

* release/3.1.1:
  [maven-release-plugin] prepare for next development iteration
  [maven-release-plugin] prepare release halbuilder-core-3.1.1
  Updated deps for latest git, using released guava 15
  Updated dependencies.
  Update guava to 15.0
  Made render public
  Interface contracts/rendering support properties
  Updated readme
Merge tag '3.1.1' into develop

Rel

* tag '3.1.1':
  [maven-release-plugin] prepare for next development iteration
  [maven-release-plugin] prepare release halbuilder-core-3.1.1