* fix missing defaultSorted props for default sort sample
* implement customized classes for sorted header
* [test] test for sorted header classes
* implement customized style for sorted header
* [test] test for sorted header style
* update document
* add missing props check and fix typo
* seperate sorting style and header into two props
* [test] add test case if column.headerStyle and column.headerClasses were defined
* implement customized header style and classes in column level
* [test] test for customized header style and classes in column level
* [DOC] document for customized classes and styles
* sample for customized classes and styles
* typo fix for document
* tuning the wording for test and documents
* beautify code block with google-code-prettify
* prettyPrint when componentDidMount
* css style for code block
* skip rule 'no-unresolved' for eslint
* conflict with webpack resolve path
* refactor all code block in example folder with component <Code />
* refactor scss folder structure
* specify the responsibility for each stylesheet with file name
* load local color themes, tomorrow, for google code prettify
* re-select demo color and save into variable
* unify the color system for storybook
* wrapper components with Decorators to set component margin
* add sticker github-corners at welcome page
* refactor welcome page for storybook
* refactor scss code structure
* add type.js to animate sub title