* Fix. Cache class.
* `send_event` raise error so `Cache.del` did not remove key or send any event
* use `memcache` method by default even if `cache` table does not defined in config
* `Cache.get` did not return any data when use `memcache` method
* `Cache.get` did not close file. (Its should not be a big problem because GC should do it by self).
* `Cache.get` can returns some undefined global value. (if method is `file` and file not exists then method returns global `result` value)
* `Cache.get` does not need check for file existence
* Value escaping does not needed for `file` method
* Needed different key escaping for `memcache` and `file` methods
* Update self test
* Change. Use random names for temp files.
