Add comment explaining empty method
Correct check box and radio button implementations; fixes #216

Conflicts:
	core/src/main/java/com/dianaui/universal/core/client/ui/CheckBox.java
	core/src/main/java/com/dianaui/universal/core/client/ui/CheckBoxButton.java
	core/src/main/java/com/dianaui/universal/core/client/ui/InlineCheckBox.java
	core/src/main/java/com/dianaui/universal/core/client/ui/InlineRadio.java
	core/src/main/java/com/dianaui/universal/core/client/ui/Radio.java
	gwtbootstrap3/src/main/java/org/gwtbootstrap3/client/ui/RadioButton.java