Dao7-1.3.1-Stable-0: Merge pull request #225 from dreamsxin/bug

Support specify the metadata cache key

Fix memory leak in method Phalcon\Di\Injectable::fireEventData
Fix memory leak in class Phalcon\Http\Client\Adapter\Curl
Fix bug in method Phalcon\Mvc\View::partial
Fix core dump in method Phalcon\Mvc\Model::findFirst

Add method Phalcon\Mvc\Url::isLocal
Add method Phalcon\Mvc\Model::exits
Add method Phalcon\Arr::aggr
Add method Phalcon\Arr::group

Add static method Phalcon\Mvc\Model::group

Add class Phalcon\ExitException
Add class Phalcon\Paginator\Adapter
Add class Phalcon\Storage\Datrie
Add class Phalcon\Storage\Lmdb
Add class Phalcon\Storage\Lmdb\Cursor
Add class Phalcon\Storage\Leveldb
Add class Phalcon\Storage\Leveldb\Iterator
Add class Phalcon\Storage\Leveldb\Writebatch