code: function getTemplate (templates, fileName) {
    var extMatch = fileName.match(/\.([^\.]*)$/);
    if (extMatch && extMatch.length > 1)
      return templates[extMatch[1]];
    return null;
  }
docs: Takes a templates hash `templates` and a fileName
  and returns a templating function if found
  
  @params {Object} templates
  @params {String} fileName
  @returns {Function|null}