Make layout more friendly for small-screen devices like phones.

1. Avoid overriding text size, assume that default one is just
good enough for any specific device out there.
2. Pack layout more tightly, put in the table only those widgets which
really should be there.
3. Use shorter strings when there's no meaning loss.
4. Wrap everything in ScrollView.
Add hint about auth tag.
Merge pull request #3 from pfalcon/pfalcon

Improve layout for small-screen devices like phones