Fix bug with forbidUndefinedVariables (#62)
Fix bug with forbidUndefinedVariables (#62)

The forbidUndefinedVariables check wrongly flagged keys that existed in other scopes as undefined, this fix checks for the key in the other scopes of the validationModel before flagging it as undefined.
JohnieLee/node-restify-validation,z0mt3c/node-restify-validation