add Url to Storage for S3 support

db/zm_create.sql.in

@@ -701,6 +701,7 @@ CREATE TABLE `Storage` (
 	`Path`	varchar(64)	NOT NULL default '',
 	`Name`	varchar(64) NOT NULL default '',
 	`Type`	enum('local','s3fs') NOT NULL default 'local',
+  `Url` varchar(255) default NULL,
   `DiskSpace`   bigint default NULL,
   `Scheme`   enum('Deep','Medium','Shallow') NOT NULL default 'Medium',
   `ServerId` int(10) unsigned,

db/zm_update-1.31.40.sql

@@ -0,0 +1,12 @@
+
+SET @s = (SELECT IF(
+    (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE table_schema = DATABASE()
+     AND table_name = 'Storage'
+     AND column_name = 'Url'
+    ) > 0,
+"SELECT 'Column Url already exists in Storage'",
+"ALTER TABLE `Storage` ADD `Url` VARCHAR(255) default NULL AFTER `Type`"
+));
+
+PREPARE stmt FROM @s;
+EXECUTE stmt;