Styleguide button elements now work when pasted into CMS WYSIWYG

[nickdenardis]

Reason for change

This resolves the issue with <div> elements inside <a> elements being stripped when copy/pasted into the CMS.

This change only affects the visible code in the styleguide. The typical <div> child elements will still be used for the template component output as they don't need to change.

Reminders

• Update package version number
• Frontend accessibility check
• Styleguide example in place
• New functionality covered by tests
• Screenshots of multiple screen sizes

Demo

Before	After

[coveralls]

coverage: 100.0%. remained the same
when pulling a00570e on feature/button-fixes
into 4d4d6d3 on develop.