Settings export refactor (#1646)

* Refactor Export to take an account and know about the export types

* Use Export instance in settings/exports#show

spec/controllers/settings/exports_controller_spec.rb

@@ -1,6 +1,8 @@
 require 'rails_helper'
 
 describe Settings::ExportsController do
+  render_views
+
   before do
     sign_in Fabricate(:user), scope: :user
   end
@@ -8,6 +10,7 @@ describe Settings::ExportsController do
   describe 'GET #show' do
     it 'returns http success' do
       get :show
+
       expect(response).to have_http_status(:success)
     end
   end