Fix resque_scheduler startup for master branch of resque_scheduler

Current master branch of resque_scheduler changed behavior of invoking  Process.daemon ( https://github.com/bvandenbos/resque-scheduler/commit/c45d9977bc1448d34fa09c94b4516e950bac0d70 )

If you don't use MUTE env var, capistrano will hang forever on resque_scheduler startup.