dashboard: change store upload input to single

circle/dashboard/templates/dashboard/store/_list-box.html

@@ -86,7 +86,7 @@
           </button>
         </span>
       </div>
-      <input id="store-upload-file" name="data" type="file" style="display:none" multiple>
+      <input id="store-upload-file" name="data" type="file" style="display:none">
     </form>
   </div>
 </div><!-- closing list-group -->

circle/dashboard/templates/dashboard/store/upload.html

@@ -26,7 +26,7 @@
           <input type="hidden" name="next" value="{{ next_url }}"/>
           <div>
             <input class="btn btn-default btn-sm pull-right" type="submit" value="{% trans "Upload" %}"/>
-            <input type="file" name="data" multiple style="padding-top: 5px;"/>
+            <input type="file" name="data" style="padding-top: 5px;"/>
           </div>
         </form>
       </div>