Merge and improve pull-request #666 (custom stylesheet)

app/Template/config/application.php

@@ -20,6 +20,9 @@
     <?= $this->formSelect('application_date_format', $date_formats, $values, $errors) ?><br/>
     <p class="form-help"><?= t('ISO format is always accepted, example: "%s" and "%s"', date('Y-m-d'), date('Y_m_d')) ?></p>
 
+    <?= $this->formLabel(t('Custom Stylesheet'), 'application_stylesheet') ?>
+    <?= $this->formTextarea('application_stylesheet', $values, $errors) ?><br/>
+
     <div class="form-actions">
         <input type="submit" value="<?= t('Save') ?>" class="btn btn-blue"/>
     </div>