limited the size of decimals to two places
Hack: keep the balance 0 after reentering the app

Right now, due to the fact that I'm using floats instead of BigDecimal -
the amounts of money are losing precision. The precision loss is very
small, nevertheless when the daily budget gets balanced and the balance is
supposed to equal zero - it still is somewhat above or below zero (due to
precision loss). This issue will be addressed in the later version by
switching to BigDecimal or longs

- make a hack that will keep the balance at 0 (visually) after
  balancing the daily budget by introducing a DAILY_BUDGET_BALANCED
  boolean variable that will keep the balance at 0 until the user does
  something with the balance in other activities.