Added Opts Definition

Author: Deepesh Mehta

index.d.ts

@@ -16,6 +16,11 @@ declare namespace fastgateway {
     type: string;
   }
 
+  interface Opts {
+    server?: Function,
+    middlewares?: Function[],
+    routes?: Route[], 
+  }
   interface Route {
     proxyType?: Type;
     fastProxy?: {};