properly set data.format and no longer hardcode local raster ids

lib/source.js

@@ -329,14 +329,12 @@ source.normalize = function(data) {
         }
         return l;
     });
-    // Format property to distinguish from imagery tiles.
-    data.format = 'pbf';
 
     // Construct vector_layers info from layer properties if necessary.
     data.vector_layers = protocolIsValid(tm.parse(data.id).protocol) === 'local'
         ? data.Layer.reduce(function(vlayers, l) {
             // Only allow one vector_layer for local raster sources.
-            if (l.Datasource.type === 'gdal') return [{id:'raster_local'}];
+            if (l.Datasource.type === 'gdal') return [{id:'undefined'}];
 
             var info = {};
             info.id = l.id;
@@ -357,6 +355,13 @@ source.normalize = function(data) {
             return vlayers;
         }, [])
         : data.vector_layers;
+
+    // Format property to distinguish from imagery tiles.
+    if(data.vector_layers !== undefined && data.vector_layers.length > 0){
+        if (data.Layer[0].Datasource.type === 'gdal') data.format = 'webp';
+        else data.format = 'pbf';
+    }
+
     return data;
 };