Add plaintext test to CodeIgniter (#4961)

* Add plaintext test to CodeIgniter

* Add plaintext to the bench config json

* Fix content type

* Small change to rerun travis

frameworks/PHP/codeigniter/application/controllers/Bench.php

@@ -9,6 +9,12 @@
 
 class Bench extends CI_Controller {
 
+    public function plaintext() {
+        $this->output
+            ->set_content_type('text/plain')
+            ->set_output('Hello, World!');
+    } 
+
     public function json() {
         $this->output
             ->set_content_type('application/json')

frameworks/PHP/codeigniter/benchmark_config.json

@@ -3,6 +3,7 @@
   "tests": [{
     "default": {
       "json_url": "/index.php/bench/json",
+      "plaintext_url": "/index.php/bench/plaintext",
       "db_url": "/index.php/bench/db",
       "query_url": "/index.php/bench/dbquery/",
       "fortune_url": "/index.php/bench/fortunes",