Add new cacheSize option to ol.source

Option added to:
 - olx.source.BingMapsOptions
 - olx.source.MapQuestOptions
 - olx.source.OSMOptions
 - olx.source.StamenOptions
 - olx.source.TileArcGISRestOptions
 - olx.source.TileImageOptions
 - olx.source.TileJSONOptions
 - olx.source.TileWMSOptions
 - olx.source.VectorTileOptions
 - olx.source.XYZOptions
 - olx.source.WMTSOptions
 - olx.source.ZoomifyOptions

src/ol/source/bingmapssource.js

@@ -24,6 +24,7 @@ goog.require('ol.tilecoord');
 ol.source.BingMaps = function(options) {
 
   goog.base(this, {
+    cacheSize: options.cacheSize,
     crossOrigin: 'anonymous',
     opaque: true,
     projection: ol.proj.get('EPSG:3857'),