ui: datastore/content: improve action button layout

Fix font-size to 14px to improve font-awesome rendering, add some
slight margin between the buttons so that they are not glued
together, add a slight text-shadow on mouse over.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/datastore/Content.js

@@ -595,7 +595,7 @@ Ext.define('PBS.DataStoreContent', {
 	    header: gettext('Actions'),
 	    xtype: 'actioncolumn',
 	    dataIndex: 'text',
-	    width: 120,
+	    width: 140,
 	    items: [
 		{
 		    handler: 'onVerify',