Fixed #13142 -- Added support for SSL connections in core.mail.backends....

...smtp

Note: SVN-based patch originally provided by serg.partizan / partizan
and Wojciech Banaś in Trac (refer to https://code.djangoproject.com/ticket/13142).

This commit includes the work done by those previous, with the following
changes:

- If use_ssl is True, or settings.EMAIL_USE_SSL is True, but the current Python
  version is less than 2.6, use_ssl is *not* internally changed to False.  Nor
  does the SMTP backend code raise an exception.  We don't need to, because Django 1.5
  is dropping support for Python prior to 2.6.

- This update provides the ability to configure the keyfile and certfile
  to use with SMTP_SSL.

- Documentation is updated to specify that this feature is new in 1.5.