made image cells downward compatibile

partials/cells/CellImage.vue

@@ -5,14 +5,14 @@
     template(v-if="display")
 
       conditional-link.fit.text-center.relative-position.linked(v-if="link", :url="link")
-        .fit(:style="cellBg")
+        .fit.downward-compatibility(:style="cellBg")
           q-btn.absolute-center.bg-primary.text-white(round, flat, size="sm")
             q-icon(v-if="link", name="link")
 
-      .fit(v-else, :style="cellBg")
+      .fit.downward-compatibility(v-else, :style="cellBg")
 
     template(v-else)
-      div.q-pa-sm.cell-background(:style="cellBg")
+      div.q-pa-sm.cell-background.downward-compatibility(:style="cellBg")
       .absolute-top-left.q-pa-sm
         cell-info(:cell="cell", type="Image Cell")
 
@@ -62,6 +62,9 @@
 <style scoped lang="stylus">
   @import '~variables'
 
+  .downward-compatibility
+    background-position center
+    background-size contain
   div
     width 100%
     height 100%