UI: Fix scaling of cover images (Fixes: #548)

This reverts f039923ac134e4a3cc70a1a7d47c21460676b1c0 and fixes #196 in
a different way (adding quotes). So that we can use the css background
properties to scale the cover images.

CHANGELOG.md

@@ -18,6 +18,7 @@ and fixes the following bugs:
 * Fix the generation and alignment of the initials avatars;
 * Only display the buttons in the board header, if the data is avialable
   and the user is able to use it;
+* Fix the scaling of cover images;
 
 Thanks to GitHub users alayek, AlexanderS, choclin, floatinghotpot, ForNeVeR,
 seschwar, and TheElf for their contributions.

client/components/cards/minicard.jade

@@ -1,8 +1,7 @@
 template(name="minicard")
   .minicard
     if cover
-      .minicard-cover
-        img(src="{{pathFor cover.url}}")
+      .minicard-cover(style="background-image: url('{{pathFor cover.url}}');")
     if labels
       .minicard-labels
         each labels

client/components/cards/minicard.styl

@@ -62,16 +62,11 @@
   .minicard-cover
     background-position: center
     background-repeat: no-repeat
-    background-size: cover
+    background-size: contain
     height: 145px
     user-select: none
     margin: -6px -8px 6px -8px
     border-radius: top 2px
-    position: relative
-
-    img
-      height: 100%
-      width: 100%
 
   .minicard-labels
     float: right