Merge branch '7-password-activity' into 'master'

Show home screen if user backs out of password activity

This borrows a technique from @grote's crash reporter patch to fix #7. If the user presses the back button in PasswordActivity, the home screen is shown. Previously, pressing the back button removed PasswordActivity from the back stack, causing the next activity in the back stack to spawn another PasswordActivity.


See merge request !41