do not show stage = 'moving' by default.
change structure of status messages.

now we have a 'tasks' field on the job that is a list of
{
    name:'',
    status:'',
    message:''
}

'status' can be one of 'processing', 'done' or 'failed'
handle and log errors when moving or copying files
restart non completed jobs upon starting.

jobs that were not finished are queued again and their messages cleaned.