Support for blocking users.
Add blocked bit to ActiveAdmin and customize the user admin a bit
Give users a bit more help with they're blocked.

Also let them log out or log in as a different user.
Tweak Gemfile.lock in a way that bundler seems to really want

Can't get it to stop making this change. Hoping this isn't an issue with conflicting versions of bundler on different machines
Fix YAML in location fixtures
Add donor mode to users for issue #12
Fix filter on "blocked" bit in user admin
Add donor mode into user admin for issue #12.

Also restrict donor mode to a defined list.
Add user balance and contributions for issue #12.

* Integrate money-rails gem
* Add balance field to User
* Add Contribution model and hooks to update balance
Add balance to admin user detail page.

Also streamline fields on index.
Add contributions into the admin interface

For issue #12. Contributions are now listed on the user admin page and can be created/deleted (but not edited).
Remove new/destroy actions from user admin.

We shouldn't be adding or deleting users from the admin panel. Users should sign up themselves; and they can be blocked, but should not be deleted.
Add price to books for issue #11

This adds a price field, editable in the admin UI. However, it does not yet have any Amazon integration. Prices have to be set by hand and aren't automatically updated. We should still do that, although this is enough to pilot the donor/volunteer program.
Fix bug in book author display.

Book would display "(by )" when author was blank but non-null.
Rework the donations sidebar on the donate page.

Now always shows unsent donations in the sidebar, even when you refresh the entire page. Rendering is separated out in JavaScript to make it easier to add complexity/features to the sidebar. Pretty soon we should just integrate Backbone or something and have real MVC, but this is a step in the right direction.
Add some "vars" that I forgot

To avoid creating global variables in JavaScript.
Always render the center div on the donate page

Even if there are no requests. This keeps the sidebar in the right place
Display book prices underneath donate button
Updates to donate page for send-money donors

Display the total of the outstanding donations, along with the donor's current balance if any. Also fixes a bug where the outstanding donations count wasn't getting updated.
Bit of cleanup on the donate page

* Always render unsent donations in time order, for consistency
* Move copy out of JS and into HTML template
* Put the "any-donations" CSS class on one div instead of a bunch of consecutive elements