Multi-currency support (#425)

* Initial foundational pass at multi-currency

* Default format currency

* More work on currency and exchanging

* Re-build currencies on change

* Currency import/setup

* Background job overhaul + cheaper OXR plan support

* Lint fixes

* Test fixes

* Multi-currency setup instructions

* Allow decimals in the balance field

* Spacing fix for form

---------

Signed-off-by: Josh Pigford <josh@joshpigford.com>

config/locales/models/account/en.yml

@@ -3,11 +3,11 @@ en:
   activerecord:
     attributes:
       account:
-        balance: Balance
-        currency: Currency
         family: Family
         family_id: Family
         name: Name
+        original_balance: Balance
+        original_currency: Currency
         subtype: Subtype
     models:
       account: Account