Add StartupActivity
Refactor "green" and "red" colors for "login" and "register"
Add activity_splash_ads in StartupActivity
In StartupActivity, refactor ads_width and ads_height to dimens
Add ADS_URL in http_urls
Display ads on StartupActivity
Add buttonRegisterPressed and buttonLoginPressed in StartupActivity
Remove .io on login_url
Registering and Login successfully will launch the MainActivity. Removed unnecessary displaySignInDialog in MainActivity