added import LegendSource, added class WMSLegendSource
added import LegendSource, added class WMSLegendSource

Anderson0026/mapproxy,mapproxy/mapproxy,faegi/mapproxy,olt/mapproxy,camptocamp/mapproxy,camptocamp/mapproxy,geoadmin/mapproxy,geoadmin/mapproxy,olt/mapproxy,kaiCu/mapproxy,kaiCu/mapproxy,faegi/mapproxy,mapproxy/mapproxy,vrsource/mapproxy,procrastinatio/mapproxy,drnextgis/mapproxy,drnextgis/mapproxy,vrsource/mapproxy,Anderson0026/mapproxy,procrastinatio/mapproxy