Merge remote-tracking branch 'upstream/master' into denormalization

Conflicts:
	lib/waterline/core/validations.js
fix create with in-exist child model
Merge branch 'denormalization'
fix create with in-exist child model, use findOne
Merge branch 'denormalization'
fix create/update parent model with in-exist child model doesn't fail
Merge branch 'denormalization'