Create model class for Employment-History questionnaire

[ryguyk]

Goal:
Model after existing forms, create for Employment History and get it working.

Potential Risks:

• Need to understand what List & Loop will generate
• spending too much time up front to generalize

Questions:

• is this something we can generalize - likely need to build form and take some time may impact schedule
• model ruby class on a performance basis - can we have a single model to handle things more generally
• what does benefits API look like-