Deleted old unncessary views in prep for UserMailer refactor
Added Trucker, the new pre-mailer logic class

(Full writeup for @Jellyfishboy )

Having spent a bit more time with Rails I now see that its preferable
for testing to remove as much logic from the mailer as possible, i.e.
just be instantiating @variables for the view and not much else. The
old mailer was doing all sorts! Even delivering its own mail. Horrid
stuff.

I have created a new class, Trucker, who takes on these excess roles,
greatly simplifying UserMailer. Trucker is well tested and does his job
just fine. This should mean you can change UserMailer to your hearts
content without endangering backend stuff.

Also in my travels I found a simpler way to set what was previously
@domain_name. The docs say as long as you say "only_path: false" in URL
helpers, you'll get the domain name too, and its set appropriately for
dev and for prod in the environment files.