Travis config : *Really* update to gafferDependencies 0.20.0.0.
Travis config : *Really* update to gafferDependencies 0.20.0.0.

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