Use default fraction digits of currency to show/edit the amount.

I change the Money class and TransactionFormFragment class to implement features below.

1. Show the default fraction digits in the account list and transaction list.
2. Use default fraction digits in new/edit transaction fragment.
   Then we can type 123 to input 123 JPY, and 1.23 USD.
   The fraction digits will use the currency default value.

I tested this change with 005SH(Japan, Version 2.3.4), GL07S(Japan, version 4.1.2).

* The same as master branch, the integration tests will throw error from 6/39. And I did not add/fix the test case to test this change.