More coverage around UI feedback for exceptions

Also explicitly inform Simplecov that yes, rspec is in fact rspec.
It was seeing the "spec/features" directory (which is a new thing in
rspec) and assuming Cucumber, which messed up merges between the
two suites.
Test shortcut gross revenue calculation method

We're not actually using this method anymore, as explained in the
comment associated with it, but as long as it's being left in (for
the sake of reviewers), it should obviously have a test.
Fix test: specify i18n lookup for validation

Oops. The message shown when an unnecessary password is given (in the
case of registering using an OpenID url) wasn't using i18n, because
only symbols are looked up - strings are used literally.
Test for validation issues on order extraction

Even though the requirements assume valid files, I wanted at least a
validation check in case that assumption was wrong.  I don't trust
assumptions, ever since the "incident" with the cauliflower and Three
Dog Night's road manager.
A whole lot of text additions and fixes

About 18% of this text is actually helpful!
A few placeholders for authentication forms