In e57f87c I moved it to a folder so that every entry in the frontends
dir was a folder. A noble goal, but it always felt silly and I'm quite
sure it will never expand to be more than a single file.
New frontends folder will hold all front-end interfaces for etiquette. Existing flask site moved here and refers to itself as a package with external launcher. etiquette_site renamed to etiquette_flask