Add 'webtiled' to valid-layer-types message.
Add 'webtiled' to valid-layer-types message.

Esri/arcgis-viewer-flex,Esri/arcgis-viewer-flex,CanterburyRegionalCouncil/arcgis-viewer-flex,CanterburyRegionalCouncil/arcgis-viewer-flex,CanterburyRegionalCouncil/arcgis-viewer-flex