ArcGis use camelcase 'Style', not lowercase 'style'

The OGC documentation is not so clear if we should use style or Style.

src/ol/source/wmtssource.js

@@ -47,6 +47,7 @@ ol.source.WMTS = function(wmtsOptions) {
   var context = {
     'Layer': wmtsOptions.layer,
     'style': wmtsOptions.style,
+    'Style': wmtsOptions.style,
     'TileMatrixSet': wmtsOptions.matrixSet
   };
   goog.object.extend(context, dimensions);