Birthday Calculator update

Today updated the Birthday Calculator Android App according to the feedback of the friend. Added these functions:

1) Instead of using keyUP() which does not work for real Android phone touch screen event, now it is using OnChange event, actually, TextWatcher is the name here.
2) Tax is added. Check the checkbox in front of Tax, then Tax is included in tip calculation.
3) The settings page is setup now. The tax rate is included in setting.

The new interface is like this: