modify get hget when return nil

when return nil,not raise an error,return emty value
Merge pull request #1 from astaxie/master

modify Get Hget when return nil
修改一些bug
修改bug
Merge pull request #2 from astaxie/master

Fixed the bug on high number of concurrent connection through one client.
Fixed the "brokenpipe" bug.
change net.Dial to net.DialTimeout, reslove lock die when redis no response.
Merge pull request #3 from 9466/patch-1

changed net.Dial to net.DialTimeout to avoid freeze when no response from redis.
add client.TimeOut, let user can set TimeOut
Merge pull request #4 from 9466/patch-3

added client.TimeOut, so that users can set TimeOut
Timeout setting was wrong.