splash-screen: Add ability to redirect to a splash screen URL

Checks for the presence of a cookie with specific values when activated,
and redirect the user to a configurable URL when it is not found, or not
with an accepted value.

To be used to display a splash screen to users upon the first visit.
It's the responsability of the splash page at the redirected URL to set
the proper cookie value before sending users back to the LMS.

Conflicts:
	CHANGELOG.rst

CHANGELOG.rst

@@ -5,6 +5,8 @@ These are notable changes in edx-platform.  This is a rolling list of changes,
 in roughly chronological order, most recent first.  Add your entries at or near
 the top.  Include a label indicating the component affected.
 
+LMS: Add ability to redirect to a splash screen.
+
 Blades: Add role parameter to LTI. BLD-583.
 
 Blades: Bugfix "In Firefox YouTube video with start time plays from 00:00:00".

lms/envs/common.py

@@ -689,6 +689,7 @@ MIDDLEWARE_CLASSES = (
     'django.contrib.messages.middleware.MessageMiddleware',
     'track.middleware.TrackMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',
+    'splash.middleware.SplashMiddleware',
 
     'course_wiki.course_nav.Middleware',
 
@@ -1096,6 +1097,9 @@ INSTALLED_APPS = (
     'django_comment_common',
     'notes',
 
+    # Splash screen
+    'splash',
+
     # Monitoring
     'datadog',
 

requirements/edx/github.txt

@@ -22,3 +22,4 @@
 -e git+https://github.com/edx/django-waffle.git@823a102e48#egg=django-waffle
 -e git+https://github.com/edx/event-tracking.git@f0211d702d#egg=event-tracking
 -e git+https://github.com/edx/bok-choy.git@v0.1.0#egg=bok_choy
+-e git+https://github.com/edx-solutions/django-splash.git@15bf143b15714e22fc451ff1b0f8a7a2a9483172#egg=django-splash