implement Http Login in Test class

바로 실행해 보면서 test class에 login 코드를 구현
app을 빌드, 배포하느냐 시간을 소비하지 않고 빠르게 구현할 수 있다.
refactoring - Http Login in Test class

- extract constant, method
move code from test to production
add failing test for resultView
make it pass for resultView
apply AsyncTask
refactor LoginHandler

- extract method by composed method pattern
add test for makeResult
add test for makeResult when response is null
implement makeResult