Hungarian SIP: folder structure should be explicit in the METS struct map

[luis100]

For every folder in the SIP create a <div>in the METS struct map.
Generate descriptive metadata for each folder based on the folder name and based on a template.

<ead:ead xmlns:ead="urn:isbn:1-931666-22-9" xmlns="urn:isbn:1-931666-22-9">
       <eadheader>
         <eadid countrycode="HU" mainagencycode="HU-MNLOL">SIP_2017-06-02_HU-MNL-OL_001</eadid>
         <filedesc></filedesc>
       </eadheader>
       <archdesc level="recordgrp">
         <did>
           <unitid>{{foldername}}</unitid>
           <unittitle>{{foldername}}</unittitle>
           <unitdate label="originated_date" normal="2015-01-01">2015-01-01</unitdate>
           <unitdate label="closed_date" normal="2015-12-31">2015-12-31</unitdate>
           <unitdate label="coverage_from" normal="2017-06-02">2017-06-02</unitdate>
           <unitdate label="coverage_to" normal="2017-06-02">2017-06-02</unitdate>
           <origination>
             <corpname>Magyar Nemezeti Levéltár Országos Levéltára</corpname>
           </origination>
           <langmaterial>
             <language>Magyar</language>
           </langmaterial>
         </did>
         <fileplan>
           <p>
             <ref/>
             <date type="classification_date"/>
           </p>
         </fileplan>
         <custodhist>
           <p>Megőrizték</p>
         </custodhist>
         <acqinfo>
           <p>Begyütt</p>
         </acqinfo>
         <accessrestrict>
           <legalstatus>open</legalstatus>
         </accessrestrict>
       </archdesc>
     </ead:ead>

[nuno-vieira-deel]

Solved. Can you review it @luis100? (commit on commons-ip here)