make sure to register stdout and stderr with launcher so we view gradle build output

[dlethin]

Also -

• updated updated mojo to use maven annotations for parameter definitions, so as to be compatible with maven 3.2 (required for travis-ci builds. Otherwise, builds will break because default parameters for plugin are not getting set correctly in the integration tests.
• updated .travis.yml definition to get rid of JDK6 since travis does not support it any longer. Switched to JDK 8