bunch of modification ... step01

* blender return exit status and complete log per rendered chunk. resulted log information is saved on server side and can be retrieved over dashboard.
* if blender encounter some problem when rendering some shot it will report an error and shot will be stopped. this is not allays true. some times blender just crash and it will need just to retry before blocking entire shot
* at time when new shot is created on server side will be created a snapshot of project and all workers will download and use that snapshot for that shot for rendering.
* eliminated active_show to be able to render shot that belongs to different projects at same time but not only shots that belong current active project or show

TODO:
* select a snapshot from a list when creating a new shot or create a new or render without snapshot
* delete unused snapshot on worker side
create a local snapshot an sync it ... step02

* a snapshot is created before we create a new shot. when creating a new shot we select desired snapshot and worker will sync it to it's local storage if not yet.
* can be inserted a comment when creating a new snapshot