Update parameter normalization, closes #14
Changelog bump
Append trailing slash if required
Clarify update_order usage

Add this to clarify that notes can be added.
Update class-wc-api-client.php
Merge pull request #21 from tillz/patch-1

Auto append trailing slash to endpoint URL, props @tillz
Merge pull request #23 from tillz/patch-2

Clarify update_order usage
Merge branch 'master-github'

Conflicts:
	README.md
	class-wc-api-client.php