secure_serialisation 0.5.0

Functions to encode/decode and encrypt/decrypt data using public-key, authenticated encryption.
Documentation
# Secure Serialisation - Change Log

## [0.5.0]
- Update rust_sodium to 0.7.0
- Update secure_serialisation::Error to implement Error trait
- Reuse facilities from rust_sodium for anonymous encryption
- Add basic example how to use encryption/decryption functions

## [0.4.0]
- Use rust 1.19 stable / 2017-07-20 nightly
- rustfmt 0.9.0 and clippy-0.0.144
- Replace -Zno-trans with cargo check
- Make appveyor script using fixed version of stable
- Use maidsafe fork of sodiumoxide
- Increase cache usage
- Add Contributor Agreement version 1.1

## [0.3.0]
- Updated dependencies

## [0.2.0]
- Satisfied Clippy (including renaming Error variants)
- Fixed tests

## [0.1.0]
- Initial structure