Update User model totalCash property

This is to accomodate latest changes on the model from iOS team
Add setup property to User model.
Add initial user flow

This flow will ask the user for its initial cash balance to have an starting point.

It marks the user setup property to true and creates its first transaction with the cash balance.
Fix up from review
Merge pull request #91 from CodePath-MAF/feature-new-user-flow

New user flow