roll more files to avoid replace old logs, temporarily fix CodisLabs#542

only handle latest action

Merge pull request CodisLabs#498 from wandoulabs/godep

use godep compulsively

update FAQ for session expired

fix bug when proxy reading redis get error

skip pre_migrate if slot is already migrating

remove unused code

rollback from pre_migrate to online if migration task failed

if there is slot migrating, proxy online should be allowed

Update config.ini