Adding courier esmtp support (INCOMPLETE)

This is the first step in adding smtp support to the courier role. Its known to
be broken (config incomplete) and the templates/vars are a nightmare.
Definitely need to set defailts in -msa and -ssl based on esmtpd variables then
provide vars to override them. Readme doesn't have all the new vars and
defaults will need to be split - its that big now.
Move imap variables out of defaults file

This file is getting out of hand so i'm moving the config in to per service
files. I'm hoping its supported...
Start merging variables

This is my first pass at removing useless variables from the defaults file.
Update esmtp configuration values

We can run the esmtp tasks though correctly now.
Move all values back in to defaults/main.yml

As best I can tell there is no way to have files other then main.yml - bit of
an oversight in my opinion.

All tasks will have to share this file until that changes so its quite long.