Add stats to config (#12023)

* Add stats to config 

Reference 
https://github.com/webpack/extract-text-webpack-plugin/issues/35#issuecomment-176689891

* Update webpack.d.ts

webpack-dev-server/webpack-dev-server.d.ts

@@ -29,7 +29,7 @@ declare module "webpack-dev-server" {
             watchOptions?: webpack.WatchOptions;
             publicPath: string;
             headers?: any;
-            stats?: webpack.compiler.StatsToJsonOptions | webpack.compiler.StatsToStringOptions;
+            stats?: webpack.compiler.StatsOptions| webpack.compiler.StatsToStringOptions;
 
             setup?(app: core.Express): void;
         }

webpack/webpack.d.ts

@@ -63,6 +63,8 @@ declare module "webpack" {
             recordsOutputPath?: string;
             /** Add additional plugins to the compiler. */
             plugins?: (Plugin|Function)[];
+            /** Stats options for logging  */
+            stats?: compiler.StatsOptions;
         }
 
         interface Entry {
@@ -482,12 +484,12 @@ declare module "webpack" {
                 /** Returns true if there were warnings while compiling. */
                 hasWarnings(): boolean;
                 /** Return information as json object */
-                toJson(options?: StatsToJsonOptions): any; //TODO: type this
+                toJson(options?: StatsOptions): any; //TODO: type this
                 /** Returns a formatted string of the result. */
                 toString(options?: StatsToStringOptions): string;
             }
 
-            interface StatsToJsonOptions {
+            interface StatsOptions {
                 /** context directory for request shortening */
                 context?: boolean;
                 /** add the hash of the compilation */
@@ -524,7 +526,7 @@ declare module "webpack" {
                 assetsSort?: string;
             }
 
-            interface StatsToStringOptions extends StatsToJsonOptions {
+            interface StatsToStringOptions extends StatsOptions {
                 /** With console colors */
                 colors?: boolean;
             }