refs https://github.com/TryGhost/DevOps/issues/50
- this switches the .eslint configs from `node` to `ts`, which is a new
config to support eslint for TypeScript
- also makes minor changes to adhere to these new rules
refs https://github.com/TryGhost/Arch/issues/46
- This module with be a placeholder for "filter expansions" we use across the codebase. For now it will only contain the expansions for the "post" resource, but any new or refactored expansions should land here too.
