GWTII-27: isShowing of AbstractServerLayer should use max scale exclusively
GWTII-27: test RasterServerLayer corrections
GWTII-30: isShowing of VectorServerLayer should use max scale exclusively
Merge pull request #94 from geomajas/GWTII-27_GWTII-30_maximumScaleExclusive

Gwtii 27 gwtii 30 maximum scale exclusive