Show search bar only for members.

ticdesk/templates/ticdesk/base.html

@@ -22,10 +22,12 @@
 
   <div class="collapse navbar-collapse" id="navbar-main">
    <ul class="nav navbar-nav ml-auto">
-    {% if user.is_authenticated %}
+    {% if user.is_member %}
      <form class="form-inline" action="{% url "ticdesk_org:person" %}" method="GET">
       <input class="form-control mr-sm-2" type="search" placeholder="Benutzername" aria-label="Search" name="uid" />
      </form>
+   {% endif %}
+   {% if user.is_authenticated %}
      <li class="nav-item dropdown">
       <a class="nav-link dropdown-toggle" data-toggle="dropdown" id="navbarDropdown" aria-expanded="false" role="button" aria-haspopup="true" href="#">
        {% blocktrans %}Veranstaltungen{% endblocktrans %}