Remove unused/orphaned files from public/ (dead code)

Remove unused/orphaned files from public/ (dead code)

In preparation for https://gitlab.com/gitlab-org/gitter/webapp/issues/2195

https://github.com/latentflip/webpack-unused

---

public\js\utils\user-sort.js is used in server code so it wasn't deleted

npm run webpack -- --config public/js/webpack.config.js --json | webpack-unused -s public

./public\js\collections\chat-search.js
./public\js\collections\equals.js
./public\js\components\notify.js
./public\js\components\oauth.js
./public\js\components\web-notifications.js
./public\js\utils\base64.js
./public\js\utils\ensure-pojo.js
./public\js\utils\locale.js
./public\js\utils\mailto-gen.js
./public\js\utils\text-filter.js
./public\js\utils\user-sort.js
./public\js\views\menu\old\orgCollectionView.js
./public\js\vue\entry-server.js
./public\js\vue\left-menu\index.js
./public\js\vue\store\actions.js
./public\js\vue\store\getters.js
./public\js\vue\store\index.js
./public\js\vue\store\mutation-types.js
./public\js\vue\store\mutations.js
./public\js\vue\store\state.js
./public\js\vue\thread-message-feed\index.js
./public\js\vue\thread-message-feed\store\index.js
./public\js\webpack.base.config.js
./public\js\webpack.config.js
./public\js\webpack.server.config.js
./public\repo\keymaster\keymaster.js
./public\repo\mocha\mocha.js
./public\repo\mutant\mutant.js