in light of the perf/size test results of Jdenticons, switch back to Identicons as the default

tst/ModelTest.php

@@ -1,6 +1,6 @@
 <?php
 
-use Jdenticon\Identicon;
+use Identicon\Identicon;
 use PrivateBin\Configuration;
 use PrivateBin\Data\Database;
 use PrivateBin\Model;
@@ -314,15 +314,8 @@ class ModelTest extends PHPUnit_Framework_TestCase
         $comment->get();
         $comment->store();
 
-        $identicon = new Identicon(array(
-            'hash'  => TrafficLimiter::getHash(),
-            'size'  => 16,
-            'style' => array(
-                'backgroundColor'   => '#fff0', // fully transparent, for dark mode
-                'padding'           => 0,
-            ),
-        ));
-        $pngdata   = $identicon->getImageDataUri('png');
+        $identicon = new Identicon();
+        $pngdata   = $identicon->getImageDataUri(TrafficLimiter::getHash(), 16);
         $comment   = current($this->_model->getPaste(Helper::getPasteId())->get()['comments']);
         $this->assertEquals($pngdata, $comment['meta']['icon'], 'icon gets set');
     }