Adding a warning about this being a development branch.

readme.rst

@@ -8,6 +8,15 @@
     :target: https://pypi.python.org/pypi/django-mailbox
 
 
+Django-Mailbox Version 5.0 Rewrite
+==================================
+
+**Warning**: These changes are in flux and will include backward-incompatible changes!
+
+
+----
+
+
 Easily ingest messages from POP3, IMAP, or local mailboxes into your Django application.
 
 This app allows you to either ingest e-mail content from common e-mail services (as long as the service provides POP3 or IMAP support),
@@ -26,4 +35,4 @@ or -- if you're in a hurry -- by using a signal receiver.
 
 .. image:: https://badges.gitter.im/Join%20Chat.svg
    :alt: Join the chat at https://gitter.im/coddingtonbear/django-mailbox
-   :target: https://gitter.im/coddingtonbear/django-mailbox?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
+   :target: https://gitter.im/coddingtonbear/django-mailbox?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge