Fix typo, ordering

 - [x] version ordering https://github.com/incuna/feincms-pages-api/commit/e3d59acbe98f06b5705aa26150e822d4abfa690b#commitcomment-5409161
 - [x] typo https://github.com/incuna/feincms-pages-api/commit/e3d59acbe98f06b5705aa26150e822d4abfa690b#commitcomment-5409165 
 - [x] classes not extending object https://github.com/incuna/feincms-pages-api/commit/e3d59acbe98f06b5705aa26150e822d4abfa690b#commitcomment-5409744
 - [x] pass `request` to `reverse` https://github.com/incuna/feincms-pages-api/commit/e3d59acbe98f06b5705aa26150e822d4abfa690b#commitcomment-5408988
 - [x] `LinksMixin` https://github.com/incuna/feincms-pages-api/commit/e3d59acbe98f06b5705aa26150e822d4abfa690b#commitcomment-5408917