blog tutorial: added string2array and array2string explicitly
blog tutorial: added string2array and array2string explicitly

git-svn-id: 61b9b1e8143c05117000ae2af61f2b96f35cce2f@3366 c7f931c7-7552-0410-b027-2fb3d89d9100

yiiext/yii,yiiext/yii,yiiext/yii