Read react-ui package.json options from rc file

[iranreyes]

Instead of only reading the configuration from the package.json, read it optionally from a config file.

• .react-uirc file in JSON or YAML format
• .react-uirc.json file
• .react-uirc.yaml, .react-uirc.yml, or .react-uirc.js file
• react-ui.config.js file exporting a JS object

Reference: https://www.npmjs.com/package/cosmiconfig