Dhii/validation-interface

# Change log
All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](http://keepachangelog.com/)
and this project adheres to [Semantic Versioning](http://semver.org/).

## [0.2] - 2018-08-29
Stable release. No code changed.

## [0.2-alpha2] - 2018-03-07
### Added
- `ValidatorFactoryInterface`

### Changed
- Using newer version of `dhii/exception-interface`

### Removed
- `SpecValidatorInterface`

### Fixed
- Added missing import for `Traversable` in `SpecAwareInterface`

## [0.2-alpha1] - 2018-03-06
### Added
- `SpecValidatorInterface`.
- `SpecAwareInterface`.
- `SubjectAwareInterface`.
- `ValidatorAwareInterface`.

## [0.1] - 2017-03-09
Initial release, containing validator and exception interfaces.