Centralize default style in `A0Theme`
Fix style for DB auth screens.
Fix auth form box styles.
Fix auth views nav buttons.
Fields icon & placeholder styles.
Update assets images.
Fix layout for 3.5" screens.
Resize icon container views to allow bigger icons.
Use A0Theme to customize touch id btn image.
Close button style.
Merge pull request #46 from auth0/chore-styleguide

Native widgets styles
Remove old .xcworkspace.
First SMS auth flow screen.

Added 'SMS' subspec.
Disable user interaction when transitioning.
Use size classes SB for example.
Modal presentation style in iPad.
Enter code screen.
Hide keyboard on tap.
Custom view for phone input.
Show SMS auth embedded in Nav controller.

Created VC to pick country code.