code: function replaceStringsInFile(name, rootDir, replacements) {
    return findFirstFile(name, rootDir)
    .then(function (path) {
      return fs.readFileAsync(path, 'utf8')
      .then(function (content) {
        return replaceContent(path, content, replacements);
      })
      .then(function (content) {
        return fs.writeFileAsync(path, content, 'utf8');
      });
  
    })
    .catch(function (error) {
      console.error(
        'we couldn\'t replace strings in file, error: \'%s\', stack: \'%s\'',
        error.toString(), error.stack
      );
      return Promise.reject(error);
    });
  }
docs: We want to replace multiple 'strings' in file. 'replacements' will be an array: [{ pattern: /pattern/, value: 'replacement' }]