Update date filter to use international date format ISO

ISO 8601 format is the standard for international date formats.
- Formats date as: YYYY-MM-DD, example  2020-06-05

https://www.w3.org/QA/Tips/iso-date

Signed-off-by: Dixsie Wolmers <dixsie@ibm.com>
Change-Id: Ic0796932b441592e998eaa8818b4f88fe8f1345d
diff --git a/src/main.js b/src/main.js
index d9f1e78..9e0502d 100644
--- a/src/main.js
+++ b/src/main.js
@@ -34,13 +34,8 @@
 
 // Filters
 Vue.filter('formatDate', function(value) {
-  const dateOptions = {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric'
-  };
   if (value instanceof Date) {
-    return value.toLocaleDateString(i18n.locale, dateOptions);
+    return value.toISOString().substring(0, 10);
   }
 });