Add 'if not exists' to system table creation. Just in case some previous db update routine was aborted or failed

SQL/mysql/2013011000.sql

@@ -1,6 +1,6 @@
 -- Upgrade from 0.9-beta
 
-CREATE TABLE `system` (
+CREATE TABLE IF NOT EXISTS `system` (
  `name` varchar(64) NOT NULL,
  `value` mediumtext,
  PRIMARY KEY(`name`)

SQL/sqlite/2013011000.sql

@@ -1,6 +1,6 @@
 -- Updates from version 0.9-beta
 
-CREATE TABLE system (
+CREATE TABLE IF NOT EXISTS system (
   name varchar(64) NOT NULL PRIMARY KEY,
   value text NOT NULL
 );