Compare amount.to_f instead of just amount in UserBalance

There was a bug that did not find a duplicate, comparing .to_f seems to
work better.
Update UserBalance tests
Remove previous_user_balance_id from UserBalance

It's not required anymore.
Add more random info to fake information

There were still collisitions happening
Fix tests for UserBalance
Fix test to match new approve method in ImportDatum
Fix test in UserBalance and UpdateBalanceHistory
Fix tests after corrections to UserBalance
Fix 'balance counts' for new way of doing things
Fix test for new 'balances' method in User
Fix remaining User tests
Fix Expense tests for modified User 'balances' method
Make get_valid_expense method accept defaults