function loadNpmConfig(file) {
  var dir = path.dirname(path.resolve(file));
  var fp  = findFile("package.json", dir);

  if (!fp)
    return null;

  try {
    return require(fp).jshintConfig;
  } catch (e) {
    return null;
  }
}
Tries to find JSHint configuration within a package.json file
(if any). It search in the current directory and then goes up
all the way to the root just like findFile.

@param   {string} file path to the file to be linted
@returns {object} config object