remove existing listed files from file upload

opentech/static_src/src/javascript/main.js

@@ -21,9 +21,11 @@ $(function () {
 
     // Show list of selected files for upload on input[type=file]
     $('input[type=file]').change(function() {
+        // remove any existing files first
+        $(this).siblings('.form__file').remove();
         for (let i = 0; i < $(this)[0].files.length; ++i) {
             $(this).parents('.form__item').prepend(`
-                <p>${$(this)[0].files[i].name}</p>
+                <p class="form__file">${$(this)[0].files[i].name}</p>
             `);
         }
     });