code: function Template(style, fields) {
    if (!~STYLES.indexOf(style))
      throw new Error("Unsupported pass style " + style);
    this.style = style;
    this.fields = {};
    for (var key in fields)
      this.fields[key] = fields[key];
    this.keysPath = "keys";
    this.images = {};
  }
docs: Create a new template.  style  - Pass style (coupon, eventTicket, etc) fields - Pass fields (passTypeIdentifier, teamIdentifier, etc)