Added the Bounce Matter component for an easier way to set restitution.

Author: photonstorm

v3/src/physics/matter-js/components/Bounce.js

@@ -0,0 +1,12 @@
+var Bounce = {
+
+    setBounce: function (value)
+    {
+        this.body.restitution = value;
+
+        return this;
+    }
+
+};
+
+module.exports = Bounce;