Add language directly to node
Add language directly to node

This is harmless and more accessible for downstream clients so they do
not have to map the validated node to the corresponding language node.

This is one of the components in migrating to supporting the new
validation implementation. See https://github.com/cbmi/avocado/wiki/Validation

murphyke/avocado,murphyke/avocado,murphyke/avocado,murphyke/avocado