BUG-509: node version is always required

This just clarifies the requirement to know the node version you are
attempting to build before instantiating a builder. Also remove some
unused methods.

Change-Id: I09406bbedee963624b43a280529d4b8cbc9931c6
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-509: node version is always required"