Fix eslint
This fixes errors such as:
Referenced from: /Users/juretriglav/src/pdk-eslint/node_modules/eslint-config-airbnb/index.js
Referenced from: /Users/juretriglav/src/pdk-eslint/node_modules/eslint-config-pubsweet/index.js
Referenced from: /Users/juretriglav/src/pdk-eslint/pubsweet/.eslintrc
Error: /Users/juretriglav/src/pdk-eslint/node_modules/eslint-config-airbnb/rules/react.js:
Configuration for rule "react/jsx-boolean-value" is invalid:
Value ["never",{"always":[]}] should NOT have more than 1 items.