Allow password-field autocomplete to be configured in settings.

This allows users to use strong passwords stored in browser password
managers, without resorting to workarounds like disabling autocomplete
everywhere.

Change-Id: I5f5e8cd332a5462bbbdc5c26bbfff2f3665016ea

horizon/conf/default.py

@@ -28,6 +28,8 @@ HORIZON_CONFIG = {
     'password_validator': {'regex': '.*',
                            'help_text': _("Password is not accepted")},
 
+    'password_autocomplete': 'on',
+
     # Enable or disable simplified floating IP address management.
     'simple_ip_management': True
 }

horizon/templates/auth/_login.html

@@ -5,7 +5,7 @@
 {% block modal_class %}login {% if hide %}modal hide{% endif %}{% endblock %}
 
 {% block form_action %}{% url login %}{% endblock %}
-{% block autocomplete %}off{% endblock %}
+{% block autocomplete %}{{ HORIZON_CONFIG.password_autocomplete }}{% endblock %}
 
 {% block modal-body %}
   <fieldset>