Clean up Validator and Mail components

- Fixed docblocks
- Removed some unnecessary returns
Merge pull request #2426 from DriesForks/dv/clean-up-validator-folder

Clean up Validator and Mail components
Added getLocale() method to Application which returns the current locale from the config.
Merge pull request #2429 from alexdover/getlocale

Added getLocale() method to Application
Fix order.
Cast to integer on limit and offset.
Merge branch '4.0'