add overlay && game do not start until the opponent came

src/Mine/SeekerBundle/Resources/public/js/mine-seeker/grid/grid-control.js

@@ -20,6 +20,9 @@ class GridControl extends React.Component {
             bombFieldCache: [],
             foundUserMineCache: 0,
             playBomb: false,
+            overlay: false,
+            overlayTitle: "",
+            overlaySubTitle: "",
             sound: {
                 click: click,
                 bomb: bomb,
@@ -366,6 +369,14 @@ class GridControl extends React.Component {
         }
     }
 
+    overlayClass() {
+        return 'game-overlay' + (
+                this.state.overlay
+                    ? ''
+                    : ' hide'
+            );
+    }
+
     render() {
         var grid = [];
 
@@ -386,6 +397,12 @@ class GridControl extends React.Component {
 
         return (
             <div className="game-wrapper">
+                <div className={this.overlayClass()}>
+                    <div className="game-overlay-window">
+                        <h1>{this.state.overlayTitle}</h1>
+                        <h2>{this.state.overlaySubTitle}</h2>
+                    </div>
+                </div>
                 <UserControl ref="userControl"
                              bombClear={this.bombClear.bind(this)}/>
                 <div className="grid"> {grid} </div>