Restore original all accounts view (with selection) on re-open after selecting individual account.

[emorikawa]

I see a minor issue in terms of how the 'All Accounts' view currently works between sessions (not sure if it is by design). To explain, when I put the app in All Accounts view, and choose Account 1, I see emails that belong to only that account as expected. When new emails come to other accounts, I can jump to the accounts in 1 click. However, if I close the app from this All Accounts view with Account 1 selected, and open the app again, N1 defaults to the Account 1 view (and not the All Accounts view with Account 1 selected). Mildly annoying.