Functional login and logout, login system should be fucntionally implemented.

Testing and polishing are next.

app/templates/login.html

@@ -19,8 +19,8 @@
 <body>
     <nav>
         <ul>
-            <li><a href="/login">Login</a></li>
-            <li><a href="/register">Create account</a></li>
+            <li><a href="{{ url_for('login.login') }}">Login</a></li>
+            <li><a href="{{ url_for('login.register') }}">Create account</a></li>
         </ul>
     </nav>
     <h1>Login to your account</h1>
@@ -29,7 +29,7 @@
     <p class="error">{{ error }}</p>
     {% endif %}
 
-    <form action="/login" method="post">
+    <form action="{{ url_for('login.login') }}" method="post">
         <label for="username">Username:</label>
         <input type="text" name="username" required />
         <label for="password">Password:</label>