The `_html` suffix was missing leading to `<br />` being displayed in
plain text. The new version also integrates the email address as a
variable in the translation.
Add a new column email_address to enterprises.
Use this new field for public display of contact details.
The old field enterprise.email is still used internally.
It is still displayed on orders and emails sent to customers.
A new enterprise has the owner's email address by default now.
Fix GH #757
