Add ability to import/export tagging rules

- Add missing translations
- Add some tests
- Add `/api/taggingrule/export` API endpoint
- Add baggy theme
- Add error message when importing tagging rules failed
- Also fix all translations (I think we are good now)

src/Wallabag/ApiBundle/Controller/TaggingRuleRestController.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Wallabag\ApiBundle\Controller;
+
+use JMS\Serializer\SerializationContext;
+use JMS\Serializer\SerializerBuilder;
+use Nelmio\ApiDocBundle\Annotation\ApiDoc;
+use Symfony\Component\HttpFoundation\Response;
+
+class TaggingRuleRestController extends WallabagRestController
+{
+    /**
+     * Export all tagging rules as a json file.
+     *
+     * @ApiDoc()
+     *
+     * @return Response
+     */
+    public function getTaggingruleExportAction()
+    {
+        $this->validateAuthentication();
+
+        $data = SerializerBuilder::create()->build()->serialize(
+            $this->getUser()->getConfig()->getTaggingRules(),
+            'json',
+            SerializationContext::create()->setGroups(['export_tagging_rule'])
+        );
+
+        return Response::create(
+            $data,
+            200,
+            [
+                'Content-type' => 'application/json',
+                'Content-Disposition' => 'attachment; filename="tagging_rules_' . $this->getUser()->getUsername() . '.json"',
+                'Content-Transfer-Encoding' => 'UTF-8',
+            ]
+        );
+    }
+}