Update FileUpload.vue

The element has a non zero size (1px X 1px) which might (and in some case actually do) cause an issue because the element actually takes some space. For example when it is placed between 2 elements with `width: 50%` the 1px will break the layout.

src/FileUpload.vue

@@ -34,6 +34,7 @@
 .file-uploads.file-uploads-html5 input,
 .file-uploads.file-uploads-html4 label {
   /* background fix ie  click */
+  position: absolute;
   background: rgba(255, 255, 255, 0);
   overflow: hidden;
   position: fixed;