adds Handlebars example

Closes #122

template_handlebars/src/README.md

@@ -0,0 +1,7 @@
+# Handlebars
+
+This is an example of how to use Actix Web with the [Handlebars templating language](https://crates.io/crates/handlebars), which is currently the most popular crate that achieves this. After starting the server with `cargo run`, you may visit the following pages:
+
+- http://localhost:8080
+- http://localhost:8080/Emma/documents
+- http://localhost:8080/Bob/passwordds

template_handlebars/src/main.rs

@@ -0,0 +1,59 @@
+#[macro_use]
+extern crate actix_web;
+
+#[macro_use]
+extern crate serde_json;
+
+use actix_web::web;
+use actix_web::{App, HttpResponse, HttpServer};
+
+use handlebars::Handlebars;
+
+use std::sync::Arc;
+
+use std::io;
+
+// Macro documentation can be found in the actix_web_codegen crate
+#[get("/")]
+fn index(hb: web::Data<Arc<Handlebars>>) -> HttpResponse {
+    let data = json!({
+        "name": "Handlebars"
+    });
+    let body = hb.render("index", &data).unwrap();
+
+    HttpResponse::Ok().body(body)
+}
+
+#[get("/{user}/{data}")]
+fn user(
+    hb: web::Data<Arc<Handlebars>>,
+    info: web::Path<(String, String)>,
+) -> HttpResponse {
+    let data = json!({
+        "user": info.0,
+        "data": info.1
+    });
+    let body = hb.render("user", &data).unwrap();
+
+    HttpResponse::Ok().body(body)
+}
+
+fn main() -> io::Result<()> {
+    // Handlebars uses a repository for the compiled templates. This object must be
+    // shared between the application threads, and is therefore passed to the
+    // Application Builder as an atomic reference-counted pointer.
+    let mut handlebars = Handlebars::new();
+    handlebars
+        .register_templates_directory(".html", "./static/templates")
+        .unwrap();
+    let handlebars_ref = web::Data::new(Arc::new(handlebars));
+
+    HttpServer::new(move || {
+        App::new()
+            .register_data(handlebars_ref.clone())
+            .service(index)
+            .service(user)
+    })
+    .bind("127.0.0.1:8080")?
+    .run()
+}