添加 Memcache 类

添加 Memcache 类 及其他修改
Revert "添加 Memcache 类"

This reverts commit 2cae1d8b3b6039e6c043ecf25db4b6ed9bb8bc86.
db
Merge remote-tracking branch 'origin/master'

Conflicts:
	config/DBConfig.php