Simplify quickstart (#142)

* Simplify silex example for use as quickstart

* Update silex README with updates

examples/silex/README.md

@@ -9,12 +9,12 @@ beginning of our application. In `web/index.php`:
 require_once __DIR__ . '/../vendor/autoload.php';
 
 // Configure and start the OpenCensus Tracer
-$exporter = new OpenCensus\Trace\Exporter\StackdriverExporter();
+$exporter = new OpenCensus\Trace\Exporter\EchoExporter();
 OpenCensus\Trace\Tracer::start($exporter);
 
 $app = new Silex\Application();
 // ... rest of the application
 ```
 
-In this example, we configured `StackdriverExporter`, but you can configure
+In this example, we configured `EchoExporter`, but you can configure
 any exporter here. You can also enable any other integrations here.

examples/silex/web/index.php

@@ -4,15 +4,22 @@
 
 // Configure and start the OpenCensus Tracer
 use OpenCensus\Trace\Tracer;
-$exporter = new OpenCensus\Trace\Exporter\StackdriverExporter();
+$exporter = new OpenCensus\Trace\Exporter\EchoExporter();
 Tracer::start($exporter);
 
 function fib($n)
 {
-    if ($n < 3) {
-        return $n;
-    }
-    return fib($n - 1) + fib($n - 2);
+    return Tracer::inSpan([
+        'name' => 'fib',
+        'attributes' => [
+            'n' => $n
+        ]
+    ], function () use ($n) {
+        if ($n < 3) {
+            return $n;
+        }
+        return fib($n - 1) + fib($n - 2);
+    });
 }
 
 $app = new Silex\Application();
@@ -21,14 +28,10 @@ function fib($n)
     return 'Hello World!';
 });
 
-$app->get('/hello/{name}', function ($name) use ($app) {
-    return 'Hello ' . $app->escape($name);
-});
-
 $app->get('/fib/{n}', function ($n) use ($app) {
     $n = (int) $n;
-    $fib = Tracer::inSpan(['name' => 'recursiveFib'], 'fib', [$n]);
-    return sprintf('The %dth Fibonacci number is %d', $n, $fib);
+    $fib = fib($n);
+    return sprintf('The %dth Fibonacci number is %d.', $n, $fib);
 });
 
 $app->run();