Show all requests to all donors

Books eligible for send-money show up with a price and the words "or
send it yourself". Others say "Not eligible for volunteer sending".
Indent requests/index.html.erb with RubyMine
Show all books together in donations sidebar 

* Donations eligible for volunteer sending are shown with a price,
  others without
* There is a summary of how many are eligible and for what total price
* Button at the bottom says “Send books” instead of “Send payment”
Use class name in case statement
Update how outstanding donations are displayed

This update starts to eliminate the differences between send_books and
send_money mode. Instead of modes, now every (eligible) donation can be
either sent by the donor, or paid for instead.

Regardless of the user's or donation's mode, the donor is assumed to be
the sender unless and until they pay for the donation.

Now when we display outstanding donations on the homepage, they are
displayed without addresses visible, but with "Send" and "Pay" buttons.
"Send" makes the address visible and also the "Book sent" button.
Alongside this are just the links you need relevant to sending: the
Amazon link, and the flag link.

"Pay" marks the book for payment, kind of like "add to cart". You can
then "pay for selected". This doesn't work yet--that's in a forthcoming
commit. You can also "pay for all" if you don't have anything selected.

There's also a new "outstanding donations" page that just lists the
outstanding donations, in the same format.

On the list of all donations, these controls aren't visible. All
donations are shown with their status. If there's anything outstanding,
it just shows up as "Not sent", and there's a warning/link to the page
where you can take care of them.
Fix a bug in the factories

Bad interaction with FactoryGirl and Timecop, relative times getting
specified at boot time. Turned them into blocks so they get specified
at runtime.
Change how flagged donations show up in sidebar

Flagged donations don't show up in the sidebar on the donate page
anymore. However, the count of flagged requests is shown.
Add Order model to relate donations and payments
Basic Order model with a bit of logic
Add an OrdersController with ability to create
Updates to Order model to fix some problems

Basically, the balance to be applied from the user was getting fixed at
Order create time. You really want it to just be the user's balance,
until the order is actually paid, at which point you want to record
permanently what balance was actually applied. So now there are derived
attributes balance_to_be_applied and new_contribution_needed, and there
are separate fields for balance_applied and new_contribution.

Also, I got rid of subtotal and just made it total, since that's what
makes more sense.

I'm modifying a migration here, but only because I know this hasn't gone
anywhere other than my own branch.
Don't automatically pay for donations

Donations should only be paid for explicitly as part of an Order. They
shouldn't be automatically covered by new contribution or an existing
balance.
Order detail page

Shows order details and either asks for a contribution or lets you pay
with a button. Button doesn't work yet though.
Fix some potential race conditions re user balance
Support for paying Orders with Contributions

Redid Order model again. This time removing all stored fields. An Order
just tracks a set of donations to be paid together, and has handy
methods to calculate things and pay them, and that's all.

When a contribution is made in the context of an order, it will now be
associated with the order and will go to pay for that order.

The order detail page is also the Amazon payment return/abandon page,
and handles those cases.
ActiveAdmin support for Orders
Refer to new page in send-money notification

This notification should now go to the send_donations page, not the old
contribution page. Note that this notification is getting merged with
the send-books notification soon anyway.
Remove obsolete code in contributions controller

Contributions are made based on orders now, so the new and thankyou
pages are obsolete. Only the create action and the test UI are needed
now.
Simplify orders controller test code a bit
Merge send-books and send-money reminders

Get rid of separate send-money reminder; rewrite send-books reminder to
indicate all options and link to the new send_donations page.