- Use PreferenceActivity, in the old style, meaning without PreferenceFragment.
- If setting Inbox, change the account settings instead of mailbox settings.
- Use the DialogWhenLarge theme, meaning it's a full-screen avitity on the
phone and a dialog on the tablet.
- Also fixed the bug that we the menu items that are made invisible by
UIControllerBase may be made re-visible by the 1-pane controller.
TODO The menu item shouldn't be shown for non-syncable mailboxes.
Change-Id: I02b2faf6f593e1e2eb370217c27801aa58ca7e6c
