refs https://github.com/TryGhost/Team/issues/905
- benefits were overridden with a secondary products query for segment select which did not have proper includes
- fixes includes for products when fetched for member segments
refs https://github.com/TryGhost/Team/issues/792
- updates product benefit to use `name` instead of `label` attribute for benefit text
- updates model/serializer/validator to correctly handle benefit attributes
- added `+` button for adding new labels as the enter behavior is closing the popup(needs fix)
refs https://github.com/TryGhost/Team/issues/792
- updates product model to read product's list of benefits
- adds transformer to return emberArray with list of product benefits
- adds new model for each product benefit
- adds validator for new product benefit
