Fix typo in deprecated class name.

IPython/html/widgets/__init__.py

@@ -12,7 +12,7 @@ from .widget_string import HTML, Latex, Text, Textarea
 from .interaction import interact, interactive, fixed
 
 # Deprecated classes
-from .widget_bool import CheckBox, ToggleButtonWidget
+from .widget_bool import CheckboxWidget, ToggleButtonWidget
 from .widget_button import ButtonWidget
 from .widget_box import ContainerWidget, PopupWidget
 from .widget_float import FloatTextWidget, BoundedFloatTextWidget, FloatSliderWidget, FloatProgressWidget

IPython/html/widgets/widget_bool.py

@@ -39,5 +39,5 @@ class ToggleButton(_Bool):
 
 
 # Remove in IPython 4.0
-CheckBox = DeprecatedClass(Checkbox, 'CheckBox')
+CheckboxWidget = DeprecatedClass(Checkbox, 'CheckboxWidget')
 ToggleButtonWidget = DeprecatedClass(ToggleButton, 'ToggleButtonWidget')