Some tweaks to get file browser back working
Added shows model

Now it is possible to create and edit shows!
Added sequences module

The system is now almost complete, since we can create
show->sequence->scene->shot. Next step is to integrate the settings
module, where we can define the current show. Without a current show
it's not possible to create sequences, and in turn scenes and shots.
Added settings model

We can now see which one is the current show!
Sequences inherit current_show id upon creation
Scenes creation allows only sequence_ids from the current show