Add microdata/json-ld to reservation notification emails

[alariva]

Add microdata or json-ld to reservation notification emails.

This would allow users to easily import the event to their Google Calendar.

Example

<div itemscope itemtype="http://schema.org/EventReservation">
  <meta itemprop="reservationNumber" content="E123456789"/>
  <link itemprop="reservationStatus" href="http://schema.org/Confirmed"/>
  <div itemprop="underName" itemscope itemtype="http://schema.org/Person">
    <meta itemprop="name" content="John Smith"/>
  </div>
  <div itemprop="reservationFor" itemscope itemtype="http://schema.org/Event">
    <meta itemprop="name" content="Foo Fighters Concert"/>
    <meta itemprop="startDate" content="2017-03-06T19:30:00-08:00"/>
    <div itemprop="location" itemscope itemtype="http://schema.org/Place">
      <meta itemprop="name" content="AT&T Park"/>
      <div itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
        <meta itemprop="streetAddress" content="24 Willie Mays Plaza"/>
        <meta itemprop="addressLocality" content="San Francisco"/>
        <meta itemprop="addressRegion" content="CA"/>
        <meta itemprop="postalCode" content="94107"/>
        <meta itemprop="addressCountry" content="US"/>
      </div>
    </div>
  </div>
</div>

As reference, JSON-LD seems to be a cool and simple package to use, but it lacks some structure items for Event.