adding decorator and demo code

demo/session_auth/templates/login.html

@@ -0,0 +1,15 @@
+{% extends 'base.html' %}
+{% block content %}
+<div>
+    <h3>Login</h3>
+    <form class="m-t" role="form" action="/login" method="post">
+        <div class="form-group">
+            <input name="username" type="text" class="form-control" placeholder="ID" required="">
+        </div>
+        <div class="form-group">
+            <input name="password" type="password" class="form-control" placeholder="Password" required="">
+        </div>
+        <button type="submit">Login</button>
+    </form>
+</div>
+{% endblock %}