added date meta

Younès El Biache · Younès El Biache · commit 188fbab910a4 · 2015-09-14T15:38:13.000+02:00
diff --git a/src/Providers/Html.php b/src/Providers/Html.php
@@ -150,6 +150,7 @@ public function getPublishedTime()
             'publication-date',
             'publish-date',
             'rc.datecreation',
+            'timestamp',
             'article:modified_time',
             'eomportal-lastupdate',
             'shareaholic:article_published_time',
