Set up code formatting with prettier and linting with eslint:

• scripts
  • lint = runs eslint with our config file on all js & json files (src & test)
  • format = formats all js & json sources
• eslint
  • Add .eslintrc.yml
  • Extend wikimedia/eslint-config-node-services
  • Extend eslint-config-prettier last to disable aesthetic rules
• prettier
  • Configure flags to be similar to eslint-config-node-services (regarding quote style and tab/spaces)