Use unique login username id.

undercover/routes.py

@@ -65,7 +65,7 @@ class CLForm(Form):
 @writing_blueprint.route('/login', methods=['POST', 'GET'])
 def login():
     if request.method == 'POST':
-        username = request.form['username']
+        username = request.form['login']
         if db.login(username, request.form['password']):
             session['username'] = username
             return redirect('/')

undercover/templates/writing.jinja2

@@ -51,9 +51,9 @@
   {% else %}
       <div class="user logged-out">
         <p>You are here as a guest.</p>
-        <form action="/login" method=post>
-          <label for="username">Username: </label>
-          <input id="username" maxlength="32" minlength="4" name="username" type="text" placeholder="sagev9000">
+        <form action="/login" method="post">
+          <label for="login">Username: </label>
+          <input id="login" maxlength="32" minlength="4" name="login" type="text" placeholder="sagev9000">
 
           <label for="password">Password: </label>
           <input id="password" maxlength="32" minlength="4" name="password" type="password">