Fix the cache key on getVoucherTotal().

Compost leaking into Store.
Voucher is not null in the sql, so make sure we look it up for all orders.
Remove dead StoreMessage and StoreMessageDisplay

They've been deprecated for a long time, and nothing uses them intentionally.
Bump package as this will break compability.

Also bumps Swat, which isn't strictly necessary, but https://github.com/silverorange/swat/pull/27 fixes a style bug related to this.
Remove all imports of store-cart.css - the pages can just include that css as well.

This makes the includes more clear.
Remove the invoice page css, which is referenced by nothing.
Update the dependencies to reflect the fact that store-cart.css is no longer imported.
Merge pull request #29 from isaacgrant/remove-css-imports

Remove all imports of store-cart.css
Merge pull request #31 from isaacgrant/store-cart-message-cleanup

Store cart message cleanup
Merge pull request #24 from isaacgrant/voucher-total

Save orders.voucher_total correctly.
prepare for release of 2.1.0
Take advantage of SwatDateEntry now defaulting to showing blank titles for its flydowns.
Merge pull request #32 from isaacgrant/swat-date-entry-blank-titles

Use new show_blank_titles flag on SwatDateEntry
Bump dependency as StoreCardExpiryEntry changes require a new Swat.
Merge pull request #33 from isaacgrant/fist-bump

Bump Swat dependency