Fix Error Handling to output JSON

[tjp2021]

All Error handling has been modified from puts statements to something more actionable. Puts statements in controller have been swapped to render json: { error handling hash }.

The error handling in both the FakepayService.rb and Customer.rb model have been changed from puts statements to return json: { error handling hash }

I'm unsure if this is the appropriate syntax or way to return json objects that have messages inside.

[speric]

I think we should write some tests for this. Do you want to pair on tests tomorrow (Monday)?

[tjp2021]

@speric That sounds good to me. Send over a calendar invite?