Bug #9254: fix point-style with "outline width" = 0 still show the outline

This PR adds OutlineStyle support to EllipseMarker and SimpleMarker point styles.

Fix bug:
http://hub.qgis.org/issues/9254.

Changes:
+ SimpleMarker (QgsSimpleMarkerSymbolLayerV2 class) supports select the style of its outline.
+ EllipseMarker (QgsEllipseSymbolLayerV2 class) supports select the style of its outline.
+ SLD files append outline style support