FIX: change software placeholder image

Refs: #900

src/Template/Element/Softwares/overview.ctp

 <div class="col-sm-6 col-md-4 col-lg-4 hidden-xs">
     <div class="size-logo-overview">
         <?php if (!$this->Software->hasLogo($software) || is_null($software->photo) || empty($software->photo)) : ?>
-            <?= $this->Html->link($this->Html->image("logos/Softwarelogo_placeholder.jpg",
-                ["alt" => $software->softwarename, "class" => "img-responsive"]),
-                "/$selectedLanguage/softwares/$software->id",
-                ['escape' => false]) ?>
+            <?= $this->Html->image("logos/placeholder_software.svg",
+                ["alt" => $software->softwarename, "class" => "img-responsive img-placeholder"]) ?>
         <?php else : ?>
             <?= $this->Html->link($this->Html->image($software->logo_directory . DS . $software->photo,
                 ["alt" => $software->softwarename, "class" => "img-responsive"]),

src/View/Helper/SoftwareHelper.php

@@ -116,7 +116,7 @@ class SoftwareHelper extends ListItemHelper
 
             $this->Html->link(
                 $this->Html->image(
-                    "logos/Softwarelogo_placeholder.jpg",
+                    "logos/placeholder_software.svg",
                     [
                         "alt" => __d("Softwares", "Go to the {0}'s page", $software->softwarename),
                         "class" => "img-responsive",