Fixed some formatting issues.
Added history field as Map<String, <TransactionHistoryItem>>.
Fixed some validation checks (i.e. will Transaction cause account
balance to go negative?)
Added logic to populate and return a Map of Account history.
Added logic to populate history on each Transaction.
Now reads history from Account and displays in a ListView.
[bug] Formatting error in Deposit/Withdrawal/TransferTransactionActivity
- "DD" part of date is off-screen!