impl-serde 0.3.0

Serde serialization support for uint and fixed hash.
Documentation 
# Changelog

The format is based on [Keep a Changelog].

[Keep a Changelog]: http://keepachangelog.com/en/1.0.0/

## [Unreleased]

## [0.2.3] - 2019-10-29
### Fixed
- Fixed a bug in empty slice serialization (https://github.com/paritytech/parity-common/pull/253)