Upgrade ContactMailer to new ActionMailer API
Upgrade OutgoingMailer to new ActionMailer API
Interpolation makes this easier to read
Upgrade some of RequestMailer to new ActionMailer API
Upgrade more of RequestMailer to new ActionMailer API

Also change name of body instance method so it doesn't collide
file_name is a string not an array
We don't need this now we're not using Rails 2.x