No UI tests & production release ready

[luongvo]

• There are no UI tests yet, which is a plus point.
  https://github.com/steve1rm/BusbyNimbleSurvey/tree/master/app/src/androidTest/java/me/androidbox/busbynimblesurvey
  https://github.com/steve1rm/BusbyNimbleSurvey/tree/master/presentation/src/androidTest/java/me/androidbox/presentation

• There is no production release config yet (proguard rules set), which is a plus point.
  https://github.com/steve1rm/BusbyNimbleSurvey/blob/master/app/proguard-rules.pro

[steve1rm]

@luongvo I have added UI screen tests here #24

[steve1rm]

@luongvo PR for release config #25