Add bootstrap version of ButtonBase
Add bootstrap version of Widget
Move base classes to org.gwtbootstrap.client.ui.gwt

Conflicts:
	core/src/main/java/com/dianaui/universal/core/client/ui/FocusWidget.java
	gwtbootstrap3/src/main/java/org/gwtbootstrap3/client/ui/FocusWidget.java
	gwtbootstrap3/src/main/java/org/gwtbootstrap3/client/ui/gwt/FocusWidget.java