refs #4053 display message in case users do not have the rights to install or update a plugin

plugins/CorePluginsAdmin/stylesheets/marketplace.less

@@ -114,6 +114,12 @@
   }
 }
 
+.pluginslistNonSuperUserHint {
+  margin-top: 30px;
+  margin-bottom: 30px;
+  width: 500px;
+}
+
 .pluginslistActionBar {
   min-width: 650px;
   max-width: 980px;

plugins/CorePluginsAdmin/templates/browsePlugins.twig

@@ -13,6 +13,13 @@
         {% include "@CorePluginsAdmin/browsePluginsActions.twig" %}
     </div>
 
+    {% if not isSuperUser %}
+        <div class="pluginslistNonSuperUserHint">
+            You can browse the list of plugins that can be installed to customize or extend your Piwik platform. Please
+            contact your administrator to get any of these installed for you.
+        </div>
+    {% endif %}
+
     <div class="pluginslist">
 
         {% if plugins|length %}

plugins/CorePluginsAdmin/templates/browseThemes.twig

@@ -13,6 +13,13 @@
         {% include "@CorePluginsAdmin/browsePluginsActions.twig" %}
     </div>
 
+    {% if not isSuperUser %}
+        <div class="pluginslistNonSuperUserHint">
+            You can browse the list of themes that can be installed to customize the appearance of the Piwik platform.
+            Please contact your administrator to get any of these installed for you.
+        </div>
+    {% endif %}
+
     <div class="pluginslist themes">
 
         {% if plugins|length %}