Improve status recording and move to metadata DB

[richardmarston]

Status should be updated at least to the following states:

• Requested (API has sent message)
• Initialising (Worker has read message)
• In progress (Simulation has commenced execution)
• Complete

[Haifischbecken]

I think it would be helpful to unify all "job" type resources accross sogno to have the same structure including a unified status.