Fix error with unsupported StageName property

Author: Aleksander Dikanski

lib/stackops/apiGateway.js

@@ -192,7 +192,7 @@ module.exports = function(currentTemplate, aliasStackTemplates, currentAliasStac
 				const baseMappingName = _.keys(baseMapping)[0];
 				const obj = baseMapping[baseMappingName];
 
-				obj.Properties.StageName = { Ref: 'ApiGatewayStage' };
+				obj.Properties.Stage = { Ref: 'ApiGatewayStage' };
 				obj.Properties.RestApiId = { 'Fn::ImportValue': `${stackName}-ApiGatewayRestApi`};
 
 				aliasResources.push(baseMapping);

test/stackops/apiGateway.test.js

@@ -749,8 +749,7 @@ describe('API Gateway', () => {
 									BasePath: '(none)',
 									DomainName: 'example.com',
 									RestApiId: { 'Fn::ImportValue': 'testService-myStage-ApiGatewayRestApi' },
-									StageName: { Ref: 'ApiGatewayStage' },
-									Stage: 'test'
+									Stage: { Ref: 'ApiGatewayStage' }
 								}
 							})
 				]));