* Implement Synth as an exchange rate provider
* Add assertions to provider interface test
* Assert the correct provider error is raised
* Remove unnecessary parens
* Support all currencies, handle outside DB
* Remove currencies from seed
* Fix account balance namespace
* Set default currency on authentication
* Cache currency instances
* Implement multi-currency syncs with tests
* Series fallback, passing tests
* Fix conflicts
* Make value group concrete class that works with currency values
* Fix migration conflict
* Update tests to expect multi-currency results
* Update account list to use group method
* Namespace updates
* Fetch unknown exchange rates from API
* Fix date range bug
* Ensure demo data works without external API
* Enforce cascades only at DB level
* Adds basic validations for required fields
Also deletes a few extraneous .keep files
Does not add the family_id required field for user, since that breaks the basic test setup
* Restore keep files to this branch
* Remove Credit model and validate models behind ids
* Restore concerns .keep
* 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>