Improve upload page

Signed-off-by: Janne Koschinski <janne@kuschku.de>

assets/sass/_page_upload.sass

@@ -57,7 +57,14 @@
         top: 0
         bottom: 0
         opacity: 0
-  .uploading.images
+  .uploading
+    display: flex
+    flex-direction: row
+    .images
+      display: flex
+      flex-direction: column
+      align-items: stretch
+      flex-grow: 1
       .detail
         .image
           position: relative