Fixes to SMTP notifications

This PR contains three things:

- added missing HTML templates under `/etc/openxpki/notification/email/`, without them I wasn't able to run notifications with default templates installed by deb package,
- added authentication step in the module - I've observed that SMTP connections were made anonymously, even if the `username` and `password` were provided in config; according to [Net::SMTP documentation](http://search.cpan.org/dist/libnet/Net/SMTP.pm) `Net::SMTP::new()` does not understand `User` nor `Password`,
- implemented module `OpenXPKI::Server::Notification::SMTP::SSL` to allow SMTP over SSL based on [Net::SMTP::SSL](http://search.cpan.org/~cwest/Net-SMTP-SSL-1.01/lib/Net/SMTP/SSL.pm), on Debian this requires `libnet-smtp-ssl-perl` package; this package is available in repos for Debian `wheezy`; I wasn't able to make `Net::SMTP::TLS` to work and `Net::SMTPS` (which looks to be also good alternative) is not available as Debian package on `wheezy` so I didn't give it try.

With theese fixes I was finally able to successfuly enable notifications on my system (which is restricted to SMTS).