GafferImageUI : Add missing import
GafferImageUI : Add missing import

This fixes errors when trying to import GafferImageUI before GafferUI, by making sure the boost::python bindings for the base classes are available.

lucienfostier/gaffer,ImageEngine/gaffer,hradec/gaffer,appleseedhq/gaffer,hradec/gaffer,andrewkaufman/gaffer,hradec/gaffer,lucienfostier/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,hradec/gaffer,boberfly/gaffer,johnhaddon/gaffer,boberfly/gaffer,GafferHQ/gaffer,hradec/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,boberfly/gaffer,andrewkaufman/gaffer,boberfly/gaffer,johnhaddon/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer