added message while logging off and removed back button from templates/base.html.
<html>
<head>
<title>{% block title %}PyTasks{% endblock %}</title>
</head>
<body>
<h2><a href="/">PyTasks</a></h2>
{% if user.is_authenticated %}
<a href="/accounts/logout">logout</a>
{% endif %}
<br><br>
{% block content %}This is the default content{% endblock %}</body>
</html>