Moved all SCSS placeholders to the root of each file since ignored otherwise

Seems bumping the node-sass version (#4827) introduced a bug (intentional or otherwise) that causes placeholders that are not at the root of the file to fail silently. So this ended up breaking a few plugins, which started working again once I moved the placeholders to the file root (so no nesting).

Also it looks like an i18n update is piggy-backing on my pull request.

/cc @nschonni @LaurentGoderre