Commit Nº: 5.
Alterações após Vídeo: Navigation with Back Up
Funcionamento ok.
Commit Inicial para Projeto Ribbit Extra (Desafio).

Extra Credit
Alternative Login

There is a "Login Activity" template available in Eclipse when creating
a new Activity. Add one to your project and take a look at the code that
is generated. It includes some helpful form validation, among other
things. See if you can replace our LoginActivity with this version (but
keep a backup in case you need to go back for the next stage!).