Travis config : Update to gafferDependencies 0.23.0.0.
Travis config : Update to gafferDependencies 0.23.0.0.

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