Gave the main billing page a sensible path name.

It should really be the `show` action on a singular `billing` resource,
but we'll get to that later.
Adopt resource-based routing for BillingController.

Includes test for manual renewal, which silently broke when we did
this.
Merged new and update billing forms into a single form.
Simplified current_user/_org helpers.
Simplified expiry date form code.

No need for Rails's weird `select_date` helper when we just need a
year.
Upgraded to Poltergeist 1.5.0.

Poltergeist is much faster, but we ran into some intermittent test
failures. The problem seems to be a race condition where we look
for the "Logout" link before the page has refreshed. Tried a few
things to make it work better, but it still fails sometimes. We're
going to live with it for now, and maybe try Capybara 2.2.
Refactor: set expiry fields only if paying by card.

We were setting those fields even if you paid with a bank account.
Refactor: unduplicated code in billings#create/update.

Most of this code should be implemented by the model, and/or just by
setting @payment.attributes = params[:payment]. But this is a safe
improvement for now.
Rewrote request specs to be request specs.

They were integration tests in disguise, using Capybara, which is
no longer supported in request specs as of Capybara 2.0.
Collect and display billing phone number.

To do: pass it along to Authorize.Net.
Wrote tests for user report CSV.

Also made a few changes:

  * removed extraneous space from City header (made feature fail)
  * added blank cells where payment info is absent
  * reduced DB query count
Added billing phone and email to user report CSV.
Wrote test for "change payment type."

Also renamed a method, for clarity.
Fixed test bug: User CSV contains hard-coded dates.

The "expected CSV data" table has to be static, so we set "today" to
something static, too.
Fixed test: todo tests fail on Saturdays.

Timecop travel to "next Tuesday" turns out to be "some Tuesday." Now
we make sure to travel to a *future* Tuesday, so the todo will be
overdue.
Wrote "cancel subscription" test.

Also fixed bug where "successfully cancelled" message didn't show up
after cancelling, because it didn't survive multiple redirects on the
way back to the dashboard.

(Should the user be redirected to the dashboard? Pending.)
Test refactor: use helper for "update subscription."
Added billing phone number to provisional accounts.
Fixed wrong payment date when changing payment type.

https://www.pivotaltracker.com/story/show/68566402
Refactor: extracted ARB subscription data methods.

Also removed superfluous `payment` parameters from a couple of
methods, and wrote a bunch of tests.