title: Image formats of theme not recognized
body: <p>I want to add Thumbnail-Settings for my theme.
  I'm using the default theme for the moment.</p>
  
  <p>There is already a image-formats.xml in the themes config.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;formats xmlns="http://schemas.sulu.io/media/formats"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://schemas.sulu.io/media/formats http://schemas.sulu.io/media/formats-1.0.xsd"&gt;
      &lt;format&gt;
          &lt;name&gt;640x480&lt;/name&gt;
          &lt;commands&gt;
              &lt;command&gt;
                  &lt;action&gt;resize&lt;/action&gt;
                  &lt;parameters&gt;
                      &lt;parameter name="x"&gt;640&lt;/parameter&gt;
                      &lt;parameter name="y"&gt;480&lt;/parameter&gt;
                  &lt;/parameters&gt;
              &lt;/command&gt;
          &lt;/commands&gt;
      &lt;/format&gt;
      &lt;format&gt;
          &lt;name&gt;1200x&lt;/name&gt;
          &lt;commands&gt;
              &lt;command&gt;
                  &lt;action&gt;scale&lt;/action&gt;
                  &lt;parameters&gt;
                      &lt;parameter name="x"&gt;1200&lt;/parameter&gt;
                  &lt;/parameters&gt;
              &lt;/command&gt;
          &lt;/commands&gt;
      &lt;/format&gt;
  &lt;/formats&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The corresponding config looks like that:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code># LIIP Theme Configuration
  liip_theme:
      themes: ["default"]
      active_theme: "default"
      load_controllers: false</code></pre>
  </div>
  </div>
  </p>
  
  <p>If i dump the images in my assets the new format (the 1200x) is not shown.
  I tried to reload the config and clear the cache. I also cleared the web/uploads/media folder.</p>
  
  <p>What else can it be?</p>
  
  <p>Here is the dump of the image in the template.
  As you see, my own format is not appearing.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>Media {#2167 ▼
    #url: "/media/12/download/1.png?v=1"
    #formats: array:10 [▼
      "400x400" =&gt; "/uploads/media/400x400/02/12-1.png?v=1"
      "400x400-inset" =&gt; "/uploads/media/400x400-inset/02/12-1.png?v=1"
      "200x200" =&gt; "/uploads/media/200x200/02/12-1.png?v=1"
      "190x" =&gt; "/uploads/media/190x/02/12-1.png?v=1"
      "170x170" =&gt; "/uploads/media/170x170/02/12-1.png?v=1"
      "150x100" =&gt; "/uploads/media/150x100/02/12-1.png?v=1"
      "100x100" =&gt; "/uploads/media/100x100/02/12-1.png?v=1"
      "100x100-inset" =&gt; "/uploads/media/100x100-inset/02/12-1.png?v=1"
      "50x50" =&gt; "/uploads/media/50x50/02/12-1.png?v=1"
      "640x480" =&gt; "/uploads/media/640x480/02/12-1.png?v=1"
    ]
    #locale: "de"
    #version: null
    #additionalVersionData: array:1 [▶]
    #fileVersion: FileVersion {#2754 ▶}
    #file: File {#2751 ▶}
    #entity: Media {#2748 ▶}
  }
  FileVersionMeta {#2759 ▼
    -id: 12
    -title: "1"
    -description: null
    -copyright: null
    -locale: "de"
    -fileVersion: FileVersion {#2754 ▼
      -name: "1.png"
      -version: 1
      -size: 105564
      -mimeType: "image/png"
      -storageOptions: "{"segment":"04","fileName":"1.png"}"
      -storageType: null
      -downloadCounter: 0
      -created: DateTime {#2742 ▶}
      -changed: DateTime {#2743 ▶}
      -id: 12
      -contentLanguages: PersistentCollection {#2761 ▶}
      -publishLanguages: PersistentCollection {#2763 ▶}
      -meta: PersistentCollection {#2758 ▶}
      -file: File {#2751 ▶}
      -tags: PersistentCollection {#2756 ▶}
      -changer: User {#2430 ▶ …2}
      -creator: User {#2430 ▶ …2}
      -defaultMeta: FileVersionMeta {#2759}
      -properties: "[]"
    }
  }</code></pre>
  </div>
  </div>
  </p>