Added JSON examples

examples/json_dynamic.rs

@@ -0,0 +1,40 @@
+//! This example illustrates the way to send and receive arbitrary JSON.
+//!
+//! This is useful for some ad-hoc experiments and situations when you don't
+//! really care about the structure of the JSON and just need to display it or
+//! process it at runtime.
+extern crate reqwest;
+#[macro_use] extern crate serde_json;
+
+fn main() -> Result<(), reqwest::Error> {
+    let echo_json: serde_json::Value = reqwest::Client::new()
+        .post("https://jsonplaceholder.typicode.com/posts")
+        .json(
+            &json!({
+                "title": "Reqwest.rs",
+                "body": "https://docs.rs/reqwest",
+                "userId": 1
+            })
+        )
+        .send()?
+        .json()?;
+
+    println!("{:#?}", echo_json);
+    // Object(
+    //     {
+    //         "body": String(
+    //             "https://docs.rs/reqwest"
+    //         ),
+    //         "id": Number(
+    //             101
+    //         ),
+    //         "title": String(
+    //             "Reqwest.rs"
+    //         ),
+    //         "userId": Number(
+    //             1
+    //         )
+    //     }
+    // )
+    Ok(())
+}