Vue.Draggable Versions Save

• correction of issue #566
• Mitigation for iisue #556 : atributes starting with data- will be copied to the DOM
• Improving wrong index calculation on edge case dnd with footer slot.
• Update to Sortbale.js v1.8.4

Correction for issue #558 and issue #555 Correction for issue #556

Using tag props instead of element. Deprecating options props in favour of transparent wrapper

Fix window not defined when running in a node environment.

• Update to sortable 1.8.3
• Fix header slot regression
• Use Webpack and vue-cli to build project

Add support to header slot.

Fix issue and issue #316 and issue #268

Update Sortable.js version to 1.7.0

Fix regression: issue#171

Fixed issue #167 issue #164

Adding footer slot as an enhancement for issue #126