First cut of two pane activity.

How to launch:
- Kick "Email 2 Pane" in the app drawer.

Major known issues:
- When you launches "Email 2 Pane", it starts directly; the logic in Welcom
  won't be executed.
- There's no UI to add accounts.  Use the old UI.
- There's no way to select non-default accounts.
- The on-screen buttons except for older/newer don't work.
- No contex menus work.

Change-Id: I38374acafafbae62e46f84294a7677e54686cfc2
2 files changed