Convert english translation file

- convert english translation to translate key
- remove baggy template for login (never used since user isn't logged in and it'll use the default theme: material)
- fix tests about text in response (now checking translation key instead of translated text)
- remove all ugly `<div class="hidden">{{ form_rest(form) }}</div>`

src/Wallabag/CoreBundle/Entity/Config.php

@@ -40,7 +40,7 @@ class Config
      * @Assert\Range(
      *      min = 1,
      *      max = 100000,
-     *      maxMessage = "This will certainly kill the app"
+     *      maxMessage = "validator.item_per_page_too_high"
      * )
      * @ORM\Column(name="items_per_page", type="integer", nullable=false)
      */
@@ -68,7 +68,7 @@ class Config
      * @Assert\Range(
      *      min = 1,
      *      max = 100000,
-     *      maxMessage = "This will certainly kill the app"
+     *      maxMessage = "validator.rss_limit_too_hight"
      * )
      */
     private $rssLimit;