use bad_request instead of invalid_request

- invalid_request will have it's argument's swallowed thus throwing away
  the custom message

[#175366070](https://www.pivotaltracker.com/story/show/175366070)

Author: weymanf

app/controllers/v3/app_manifests_controller.rb

@@ -70,7 +70,7 @@ def compound_error!(error_messages)
   def validate_content_type!
     if !request_content_type_is_yaml?
       logger.error("Context-type isn't yaml: #{request.content_type}")
-      invalid_request!('Content-Type must be yaml')
+      bad_request!('Content-Type must be yaml')
     end
   end
 
@@ -81,7 +81,7 @@ def request_content_type_is_yaml?
   def parsed_app_manifest_params
     parsed_application = parsed_yaml['applications'] && parsed_yaml['applications'].first
 
-    raise invalid_request!('Invalid app manifest') unless parsed_application.present?
+    raise bad_request!('Invalid app manifest') unless parsed_application.present?
 
     parsed_application
   end

app/controllers/v3/space_manifests_controller.rb

@@ -83,7 +83,7 @@ def compound_error!(error_messages)
   def validate_content_type!
     if !request_content_type_is_yaml?
       logger.error("Content-type isn't yaml: #{request.content_type}")
-      invalid_request!('Content-Type must be yaml')
+      bad_request!('Content-Type must be yaml')
     end
   end
 

spec/request/space_manifests_spec.rb

@@ -669,7 +669,7 @@
           parsed_response = MultiJson.load(last_response.body)
 
           expect(last_response).to have_status_code(400)
-          expect(parsed_response['errors'].first['detail']).to eq('The request is invalid')
+          expect(parsed_response['errors'].first['detail']).to eq('Bad request: Content-Type must be yaml')
         end
       end
 
@@ -692,7 +692,7 @@
           parsed_response = MultiJson.load(last_response.body)
 
           expect(last_response).to have_status_code(400)
-          expect(parsed_response['errors'].first['detail']).to eq('The request is invalid')
+          expect(parsed_response['errors'].first['detail']).to eq('Bad request: Content-Type must be yaml')
         end
       end
 

spec/unit/controllers/v3/app_manifests_controller_spec.rb

@@ -148,7 +148,7 @@
           post :apply_manifest, params: { guid: app_model.guid }, body: request_body.to_yaml
           expect(response.status).to eq(400)
           # Verify we're getting the InvalidError we're expecting
-          expect(CloudController::Errors::ApiError).to have_received(:new_from_details).with('InvalidRequest', 'Content-Type must be yaml').exactly :once
+          expect(CloudController::Errors::ApiError).to have_received(:new_from_details).with('BadRequest', 'Content-Type must be yaml').exactly :once
         end
       end
     end

spec/unit/controllers/v3/space_manifests_controller_spec.rb

@@ -205,7 +205,7 @@
           post :apply_manifest, params: { guid: space.guid }, body: request_body.to_yaml
           expect(response.status).to eq(400)
           # Verify we're getting the InvalidError we're expecting
-          expect(CloudController::Errors::ApiError).to have_received(:new_from_details).with('InvalidRequest', 'Content-Type must be yaml').exactly :once
+          expect(CloudController::Errors::ApiError).to have_received(:new_from_details).with('BadRequest', 'Content-Type must be yaml').exactly :once
         end
       end