Allow to construct Data instances to avoid double Arc for Send + Sync types.

src/app.rs

@@ -95,8 +95,8 @@ where
     ///                 web::get().to(index)));
     /// }
     /// ```
-    pub fn data<S: 'static>(mut self, data: S) -> Self {
-        self.data.push(Box::new(Data::new(data)));
+    pub fn data<U: Into<Data<U>> + 'static>(mut self, data: U) -> Self {
+        self.data.push(Box::new(data.into()));
         self
     }
 
@@ -301,14 +301,14 @@ where
     /// lifecycle (request -> response), modifying request/response as
     /// necessary, across all requests managed by the *Application*.
     ///
-    /// Use middleware when you need to read or modify *every* request or 
+    /// Use middleware when you need to read or modify *every* request or
     /// response in some way.
     ///
-    /// Notice that the keyword for registering middleware is `wrap`. As you 
+    /// Notice that the keyword for registering middleware is `wrap`. As you
     /// register middleware using `wrap` in the App builder,  imagine wrapping
     /// layers around an inner App.  The first middleware layer exposed to a
     /// Request is the outermost layer-- the *last* registered in
-    /// the builder chain.  Consequently, the *first* middleware registered 
+    /// the builder chain.  Consequently, the *first* middleware registered
     /// in the builder chain is the *last* to execute during request processing.
     ///
     /// ```rust