fix(Server): cascade stats options

Author: yoannmoinet

lib/Server.js

@@ -91,6 +91,7 @@ class Server {
       throw new Error("'filename' option must be set in lazy mode.");
     }
 
+    this.stats = Object.assign({}, STATS, options.stats);
     this.hot = options.hot || options.hotOnly;
     this.headers = options.headers;
     this.progress = options.progress;
@@ -144,7 +145,7 @@ class Server {
       compile.tap('webpack-dev-server', invalidPlugin);
       invalid.tap('webpack-dev-server', invalidPlugin);
       done.tap('webpack-dev-server', (stats) => {
-        this._sendStats(this.sockets, stats.toJson(STATS));
+        this._sendStats(this.sockets, stats.toJson(this.stats));
         this._stats = stats;
       });
     };
@@ -817,7 +818,7 @@ class Server {
           return;
         }
 
-        this._sendStats([connection], this._stats.toJson(STATS), true);
+        this._sendStats([connection], this._stats.toJson(this.stats), true);
       });
 
       socket.installHandlers(this.listeningApp, {