Expose the Django INSTALLED_APPS setting.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -4,6 +4,7 @@
 * Fix user groups view.
 * Add no results help text to the document type -> metadata type
   association view.
+* Expose the Django INSTALLED_APPS setting.
 
 3.1.2 (2018-09-21)
 ==================

mayan/apps/common/settings.py

@@ -236,6 +236,16 @@ setting_home_view = namespace.add_setting(
         'Name of the view attached to the branch anchor in the main menu.'
     ),
 )
+setting_django_installed_apps = namespace.add_setting(
+    global_name='INSTALLED_APPS',
+    default=settings.INSTALLED_APPS,
+    help_text=_(
+        'A list of strings designating all applications that are enabled '
+        'in this Django installation. Each string should be a dotted '
+        'Python path to: an application configuration class (preferred), '
+        'or a package containing an application.'
+    ),
+)
 setting_django_login_url = namespace.add_setting(
     global_name='LOGIN_URL',
     default=settings.LOGIN_URL,