Addind validation key class
Refactoring ValidationSet to grab all the keys before validating anything
Working on ValidationValue
Adding tests to increase coverage
Working on possibility to add message and keys to delegated validators
Working on making ValidationSet cope with ValidationValue functionality
Fixing some validators' error messages
Merge branch 'develop' into feature/advanced-set-validation
Finished work on add key-value and set message
Finishing advanced set validation
Merge branch 'feature/advanced-set-validation' into develop