Explicitly create the Omniauth hash

I notice that the test fails in Github with the error

```
undefined method `[]' for nil:NilClass
     # ./app/controllers/auth_services_controller.rb:48:in `create'
     # ./spec/features/member_portal_spec.rb:95:in `block (3 levels) in <top (required)>'
     # ./spec/spec_helper.rb:114:in `block (2 levels) in <top (required)>'
```

I think this is because we don't set the Gihub auth mock. It could be set elsewhere, and that might be why the test is flakey. I've explicitly set it here to try to get the tests working consistently

Author: jonodrew

spec/features/member_portal_spec.rb

@@ -92,6 +92,7 @@
     end
 
     it 'is redirected to sign_in page when they attempt not access the profile page' do
+      mock_github_auth
       visit profile_path
 
       expect(page).to_not have_selector('#member_profile')