Can't log null log message, stupid!
First, prevent multiple instances of ShowsActivity right below each other.
Second, create new task stacks when coming from notification.
Third, handle onNewIntent in ShowsActivity.

- Not useful right now, but if we ever launch ShowsActivity with an
intent containing a tab index extra and do not create a new task stack,
it will behave as expected.
Fourth, keep ListWidgetConfigure activity in its own task.

- Also clear any previous ListWidgetConfigure activities, so going back
immediately drops you to the home screen.
Merge branch 'task-stack-fixes' into beta