Steps should not be saved in project database

[TTalex]

We should create a Steps database, with the following fields:

• project_id INT (Foreign key to project db)
• step_number INT
• name STRING (Human readable name for the step)
• value STRING (JSON as string)
  Uniqueness on (project_id, step_number)

We could also add a current_step field to the project database to know what to look for in the Steps db