Fixed GafferTest.PathFilterTest.
Fixed GafferTest.PathFilterTest.

It was using an empty directory, and therefore testing nothing much at all.

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