Added test coverage for {{max}} and {{count}}
Added test coverage for {{max}} and {{count}}

refs https://github.com/TryGhost/Team/issues/510

- {{max}} and {{count}} variable usage was not covered but had valid usecases in the library client's, so considered to "document" them through tests
- For more context these variables are available in custom `error` templates that are provided with each limit

TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost