Putback user::site(), add heading for order emails

app/User.php

@@ -133,6 +133,16 @@ class User extends Authenticatable
 			->with(['account','product','invoices.items.tax','type']);
 	}
 
+	/**
+	 * The site this user is configured to access
+	 *
+	 * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
+	 */
+	public function site()
+	{
+		return $this->belongsTo(Site::class);
+	}
+
 	/**
 	 * This users supplier/reseller
 	 *