Normalize paths, joined with project's root path
NOTE: The directory with package.json is considered a project's root directory.
npm install --save root-path
var root = require('root-path');
var x1 = root();
// returns {PROJECT_ROOT}
var x2 = root('path');
// returns {PROJECT_ROOT}/path
var x3 = root('path1', 'path2');
// returns {PROJECT_ROOT}/path1/path2