metadata: allow to select which metadata tags to include in the output image

(cherry picked from commit ed64206cb8b4455870815e2c51aecbd5c09e4054)

rtdata/images/svg/tick.svg

@@ -17,8 +17,8 @@
    inkscape:export-filename="/tmp/template.png"
    inkscape:export-xdpi="96"
    inkscape:export-ydpi="96"
-   inkscape:version="0.92.2 2405546, 2018-03-11"
-   sodipodi:docname="tick-large.svg">
+   inkscape:version="0.91 r13725"
+   sodipodi:docname="tick.svg">
   <sodipodi:namedview
      id="base"
      pagecolor="#E0E1E2"
@@ -33,9 +33,9 @@
      inkscape:current-layer="layer1"
      showgrid="true"
      inkscape:window-width="1920"
-     inkscape:window-height="1019"
+     inkscape:window-height="1017"
      inkscape:window-x="0"
-     inkscape:window-y="0"
+     inkscape:window-y="30"
      inkscape:window-maximized="1"
      inkscape:grid-bbox="true"
      inkscape:pagecheckerboard="false"
@@ -63,7 +63,7 @@
         <dc:format>image/svg+xml</dc:format>
         <dc:type
            rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
-        <dc:title></dc:title>
+        <dc:title />
         <dc:creator>
           <cc:Agent>
             <dc:title>Maciej Dworak</dc:title>
@@ -103,7 +103,7 @@
        sodipodi:nodetypes="ccccccc"
        inkscape:connector-curvature="0"
        id="path2996-6"
-       d="M 4.6666624,10.166665 8.3333305,13.833335 19.333336,2.833329 23.000006,6.4999972 8.3333305,21.166671 0.99999442,13.833335 Z"
+       d="M 6.0000005,10.299997 9.0000007,13.533332 18.000004,3.833329 21.000006,7.066663 9.0000007,20 3,13.533332 Z"
        style="opacity:0.7;fill:#2a7fff;fill-opacity:1;stroke:none;stroke-width:2.30911016" />
   </g>
 </svg>