Merge pull request #166 from quailjs/refactor-to-classes

Case, Test and TestCollection classes with unit tests.
Remove OAC color tests
Removed color body attributes.
Moved quail.colors into the component scope.
Tagged documentIDsMustBeUnique with technique H93. Fixes #167
Merge branch 'remove-oac-color' into dev
Converted all strings into collections.
Updated skipToContentLinkProvided to check text content and focus visibility. #176
Fixed error where attributes could be undefined in building selector.
Merge branch 'refs/heads/dev' into guideline