added reverse proxy configuration form and handler

cps/admin.py

@@ -347,6 +347,10 @@ def _configuration_update_helper():
 
     _config_int("config_updatechannel")
 
+    # Reverse proxy login configuration
+    _config_checkbox("config_allow_reverse_proxy_header_login")
+    _config_string("config_reverse_proxy_login_header_name")
+
     # GitHub OAuth configuration
     if config.config_login_type == constants.LOGIN_OAUTH:
         active_oauths = 0

cps/templates/config_edit.html

@@ -271,6 +271,16 @@
         </div>
       {% endif %}
     {% endif %}
+        <div class="form-group">
+          <input type="checkbox" id="config_allow_reverse_proxy_header_login" name="config_allow_reverse_proxy_header_login" data-control="reverse-proxy-login-settings" {% if config.config_allow_reverse_proxy_header_login %}checked{% endif %}>
+          <label for="config_allow_reverse_proxy_header_login">{{_('Allow Reverse Proxy Authentication')}}</label>
+        </div>
+        <div data-related="reverse-proxy-login-settings">
+          <div class="form-group">
+            <label for="config_reverse_proxy_login_header_name">{{_('Reverse Proxy Header Name')}}</label>
+            <input type="text" class="form-control" id="config_reverse_proxy_login_header_name" name="config_reverse_proxy_login_header_name" value="{% if config.config_reverse_proxy_login_header_name != None %}{{ config.config_reverse_proxy_login_header_name }}{% endif %}" autocomplete="off">
+          </div>
+        </div>
       </div>
     </div>
   </div>