Adds *.xcbkptlist to gitignore
AppDelegate uses BalanceViewController as root

   + Inject the BalanceService into the BalanceViewController
   + BalanceViewController extends UITableViewController
   + Removes the navigation controller for now
Displays balance in controller's UITableView

   + Adds TestBalanceService for mocking this injected dependency
   + Implements UITableViewDataSource protocol for BalanceViewController
   + Adds storyboard for BalanceViewController
Adds TransactionRequest
Adds transaction service for fetching transactions
Loads transactions into table view