Function add

local-cli/util/PackageManager.js:52–57

* Install package into project using npm or yarn if available * @param {[type]} packageName Package to be installed * @return {[type]} spawnSync's result object

(packageName)

 * @return {[type]}             spawnSync's result object
 */
function add(packageName) {
  return callYarnOrNpm(
    `yarn add ${packageName}`,
    `npm install ${packageName} --save`
  );
}

/**
 * Uninstall package from project using npm or yarn if available