With Resharper it can be done in two steps.
Set the checkbox "Add 'using' directive to the deepest scope" in Code Editing
→ C#
→ Code Style
→ Reference qualification
.
In the context menu of the solution choose "Cleanup Code...".
You might want to create a custom cleanup pofile that suits your needs before performing the cleanup.
In ReSharper before v9 the setting is located somewhere else:
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…