Only do special treatment for own user activity if it's used as toplevel
activity.
Don't suppress activity recreations due to configuration changes.

This prevents e.g. having per-orientation layouts. The loaded data is
retained during the recreations in the loader instances.
Fix attribute parsing.
Convert action bar to ToolBar + separate tab view.

Brings more fancy tabs for now and will allow more seamless integration
between action bar and content (e.g. in the issue activity) later.
Tune drawer item layout to latest spec.

Still needs icons, though.