Eslint tweaks (#696)

* make eslint styleguide into warnings & drop no-else-return

* reintroduce max-warnings=0

* remove unnecessary eslint line disable

* reintroduce no-else-return rule

.lintstagedrc.js

@@ -7,7 +7,7 @@ const cli = new CLIEngine({});
 module.exports = {
   "*.{js,ts,tsx}": files => {
     return (
-      "eslint --fix " + files.filter(file => !cli.isPathIgnored(file)).join(" ")
+      "eslint --max-warnings=0 --fix " + files.filter(file => !cli.isPathIgnored(file)).join(" ")
     );
   },
   "*.{css,scss,json,md,html,yml}": ["prettier --write"],