Gradle migration: add private Maven repos and compile for Java 1.6
Gradle migration: add private Maven repos and compile for Java 1.6

ow2-proactive/programming,paraita/programming,lpellegr/programming,paraita/programming,fviale/programming,lpellegr/programming,ow2-proactive/programming,fviale/programming,fviale/programming,ow2-proactive/programming,lpellegr/programming,fviale/programming,paraita/programming,lpellegr/programming,paraita/programming,fviale/programming,fviale/programming,ow2-proactive/programming,lpellegr/programming,paraita/programming,paraita/programming,lpellegr/programming,ow2-proactive/programming,ow2-proactive/programming