0.2.0

CHANGES:

• Add custom to_yaml and of_yaml attributes (#38, @patricoferris)
• Add skip_unknown flag to allow partially decoding yaml (#40, @code-ghalib)
• Hide record fields with default values in to_yaml output (#37, @maurobringolf, reviewed by @sim642 and @patricoferris)
• Expose to_yaml and of_yaml derivers with yaml being an alias (#36, @patricoferris)
• Improved error messages (#32, @prosper74, reviewed by @patricoferris)
• Add a default attribute for providing placeholder values (#31, @prosper74, reviewed by @ayc9, @pitag-ha and @patricoferris)