Added level to rules (#267)
Added level to rules (#267)

closes #208

- All rules have to have 'level' property otherwise this was causing an error in formatter: https://github.com/TryGhost/gscan/blob/68311e6/lib/format.js#L80
- Possible optimization could be done in the rule merge step:`https://github.com/TryGhost/gscan/blob/43c727e/lib/specs/v2.js#L824-L826 , where `level` would also be inherited from `previousRules` but that's something that needs more investigation for any side effects.
TryGhost/gscan