Enhance documentation and create a form to create a new client

src/Wallabag/CoreBundle/Form/Type/ClientType.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace Wallabag\CoreBundle\Form\Type;
+
+use Symfony\Component\Form\AbstractType;
+use Symfony\Component\Form\CallbackTransformer;
+use Symfony\Component\Form\Extension\Core\Type\SubmitType;
+use Symfony\Component\Form\Extension\Core\Type\UrlType;
+use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+class ClientType extends AbstractType
+{
+    public function buildForm(FormBuilderInterface $builder, array $options)
+    {
+        $builder
+            ->add('redirect_uris', UrlType::class, array('required' => true))
+            ->add('save', SubmitType::class)
+        ;
+
+        $builder->get('redirect_uris')
+            ->addModelTransformer(new CallbackTransformer(
+                function ($originalUri) {
+                    return $originalUri;
+                },
+                function ($submittedUri) {
+                    return array($submittedUri);
+                }
+            ))
+        ;
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
+    {
+        $resolver->setDefaults(array(
+            'data_class' => 'Wallabag\ApiBundle\Entity\Client',
+        ));
+    }
+
+    public function getBlockPrefix()
+    {
+        return 'client';
+    }
+}