Support libsass based projects
This commit removes Compass as a dependency from medium-editor. This enables us to keep 100% within the JS realm. Combined with autoprefixer Compass becomes redundant for this project and by ignoring old vendor-prefixes using autoprefixer we can also enjoy a 54% total size reduction for the CSS files.
Fix imports in themes
Merge pull request #168 from jmagnusson/no-compass

No compass
Updates dist files
Formatting Gruntfile
Updated "subscript" toolbar button markup

it was mistakenly opening a <sub> but closing it with </sup>.
Merge pull request #171 from litera/patch-1

Updated "subscript" toolbar button markup
Updates dist and src files
Do not show anchor preview for empty of # links, issue #167