This fixes an issue with Python 2.7+ where Python now silences by
default the output generated by DeprecationWarning. Django relies
on this outpt to signal to developers that they are using a feature
that is going to go away soon. This change documents this fact
and mentions how to restore them in the Release Process docs. It
also includes a small change to the default manage.py used by
startproject to restore DeprecationWarning to new projects.