Add basic element styles to Panel Expansion title button

• Add basic element styles to Panel Expansion title button

Refactor Toggle component to use toggle-icon from suomifi-icons

• Refactor Toggle component to use toggle-icon from suomifi-icons
• Add option for Panel expansion content to have no padding
• Refactor so that Menu component has the original className prop and MenuButton has other props but it's className is menuButtonClassName

Panel.expansion-component's alpha version

• Panel.expansion-component's alpha version
• a lot of bug fixes, a11y fixes and refactoring

Toggle-component's alpha version

• Dropdown-component's alpha version
• Toggle-component's alpha version
• Menu-component's basic alpha version
• Menu.language-component's alpha version
• Update README's
• Use snapshot serializer for CSS in JS
• Change TarvisCI to CIrcleCI

No clean-css dependency

• Export suomifiTheme and Icon-component
• Update normalize.cssinjs to 1.0.5 that has no clean-css dependency

Alpha release with Button-component (and dependencies)

Button-component with Icon component that uses suomifi-icon.