Allow changing the format of the contents of the email

[JeffersonBledsoe]

Allow the email that is sent to either be styled as a list (current behaviour) or as a table (new behaviour from this PR).

## Markup of emails

List:

<p>A new form has been submitted from <strong>Form</strong>:</p>
  <ul>
    
      <li>
          <strong>Field 1:</strong> List
      </li>
    
  </ul>

Table:

 <table>
    <caption>Email results for Form</caption>
    <thead>
      <tr role="row">
        <th scope="col" role="columnheader">Field</th>
        <th scope="col" role="columnheader">Value</th>
      </tr>
    </thead>
    <tbody>
      
        <tr role="row">
          <th scope="row" role="rowheader">Field 1</th>
          <td>Table</td>
        </tr>
      
    </tbody>
  </table>

fixes pretagov/nsw-demo#266

[JeffersonBledsoe]

@cekk I still need to sort out the i18n side of this PR (I've not done PageTemplate i18n before), just wanted to get your thoughts early on 🙂

[JeffersonBledsoe]

@cekk I made a few of the changes you brought up. Not sure if I should update the locales or if that's to be done as part of a release.

[cekk]

@cekk I made a few of the changes you brought up. Not sure if I should update the locales or if that's to be done as part of a release.

Yes, feel free to update locales to add new translations.

[JeffersonBledsoe]

@cekk Thanks for checking over this again. I've updated the locales now too.

Once this and #24 are merged, any chance of a release?

[cekk]

yes, will release with all the changes