Removes tag management from administrative backend

This is a precursor to only permitting pre-existing tags when creating
articles.
Merge pull request #26 from moneyadviceservice/remove-tag-management

Removes tag management from administrative backend
Adjust the layout of the article_page
Merge pull request #27 from moneyadviceservice/article-page

Adjust the layout of the article_page
Add underline to wysiwyg tool bar
Remove strike from wysiwyg tool bar
Merge pull request #29 from moneyadviceservice/wysiwyg-underline

Wysiwyg underline
Remove unnecessary files
Fix collapsing layouts
Add sharing buttons
Add SVG icons to sharing buttons
Add sharing buttons with PNG fallback for IE8
Add description and render in article demo page
Make li items more explicit
Add feature test for sharing buttons