vicky, dashboard: Additional fields for a better UI experience

[johannwagner]

We want to add at least the following fields for our tasks:

• created - Timestamp
• started - Timestamp
• closed - Timestamp
• author - Foreign key to user
• parent - Foreign key to other task
• creator - Foreign key to user

Author is the person, which started the chain.
Creator is the account, which created the task.
If a task creates another task, the author should be propagated.

[johannwagner]

This is partly implemented by #7.

[johannwagner]

We might have to think about this a bit more:

Currently, most tasks are going to be scheduled by a machine, therefore there is no user to assign to. But I would like to see, which machine token scheduled the task.

Also, if a task is scheduled by another task, it might transfer the author/creator.

Also, I would like to see a functionality to schedule a pre-defined task from the web interface.