Review my week1 assignment tip calculator

[anand99]

The assignment is here: https://github.com/anand99/android/tree/master/tip_calculator
Please review it. /cc @nesquena @timothy1ee

[nesquena]

Hi @anand99, reviewed your TipCalculator and everything looks good. Next week, we will start digging into the next Android concepts such as networking in order to build a more dynamic application. Let us know if you have any questions here or on the canvas discussion board.