Storing performed bank transactions in database

Addressing issue #11 
Test version: http://transaction-info.st-angular-js-bank.appspot.com/

Information about performed deposits and withdraws is stored in datastore.
The following screenshot shows how information is displayed for transactions performed a couple of minutes ago:
![screenshot from 2014-10-14 11 22 37](https://cloud.githubusercontent.com/assets/6047637/4625894/a986431e-537b-11e4-962c-10b98fbe9652.png)

As AngularJS's date filter automatically converts the time zone to the one of the client browser, no further actions need to be performed to ensure correct displaying of datetime information to the client.