Update ja_resource and check if controller warnings are eliminated

[begedin]

Problem

ja_resource relies on a __using__ macro to decorate our controllers. With the recent elixir upgrade, this started triggering a lot of warnings in our controllers.

There is a recent release which should eliminate a lot of these warnings, so we should update and reopen the issue in their repo if we still have trouble.

References

vt-elixir/ja_resource#49