add english lang everywhere && add snowfall && add centralized version nbr && improve stylesheet && slack integration

src/Mine/SeekerBundle/Resources/public/css/style.mineseeker.css

@@ -959,3 +959,28 @@ main {
 #mine-wrapper .grid .field-wrapper .field img {
     width: 80%;
 }
+
+.back-from-game {
+    display: inline-block;
+    position: fixed;
+    top: 20px;
+    left: 20px;
+
+    -ms-transform: scale(1); /* IE 9 */
+    -webkit-transform: scale(1); /* Safari */
+    transform: scale(1);
+    -webkit-transition: all 250ms cubic-bezier(.17,.67,.83,.67);
+    transition: all 250ms cubic-bezier(.17,.67,.83,.67);
+}
+
+.back-from-game img {
+    width: 100px;
+}
+
+.back-from-game:hover {
+    -ms-transform: scale(1.2); /* IE 9 */
+    -webkit-transform: scale(1.2); /* Safari */
+    transform: scale(1.2);
+    -webkit-transition: all 250ms cubic-bezier(.17,.67,.83,.67);
+    transition: all 250ms cubic-bezier(.17,.67,.83,.67);
+}