v3(services): use SIs name when binding name is not set

[#173129426](https://www.pivotaltracker.com/story/show/173129426)

Author: Derik Evangelista

app/presenters/v3/service_credential_binding_presenter.rb

@@ -8,7 +8,7 @@ class ServiceCredentialBindingPresenter < BasePresenter
           def to_hash
             {
               guid: @resource.guid,
-              name: @resource.name,
+              name: @resource.name || @resource.service_instance.name,
               created_at: @resource.created_at,
               updated_at: @resource.updated_at,
               type: type

spec/unit/presenters/v3/service_credential_binding_presenter_spec.rb

@@ -62,6 +62,16 @@ module CloudController
             }
           )
         end
+
+        context 'when name is not set' do
+          let(:instance) { ServiceInstance.make(name: 'smashed-avocado') }
+          let(:credential_binding) { ServiceBinding.make(service_instance: instance) }
+
+          it 'should return the service instance name as the binding name' do
+            presenter = described_class.new(credential_binding)
+            expect(presenter.to_hash[:name]).to eq('smashed-avocado')
+          end
+        end
       end
 
       describe 'key bindings' do