Fix: update S3 url for handling china region

[bartleboeuf]

Issue #213 :

Description of changes:

• Handle S3 url for S3 in AWS Mainland China in case of template upload.

Tests:

• Tests are made in our CI/CD environment in Beijing region :

DEBUG: Preparing template 'main.yml'
DEBUG: Loading AWS config
DEBUG: Artifact bucket: cf-templates-m89vz00plzen-cn-north-1
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: transform path: Resources/*|Type==AWS::CloudFormation::Stack/Properties/TemplateURL
DEBUG: Checking current status of stack 'stack-tools-non-production-main'
DEBUG: Stack exists
DEBUG: Handling parameters
DEBUG: Creating change set
DEBUG: Template is too large to deploy directly; uploading to S3.
DEBUG: Artifact bucket: cf-templates-m89vz00plzen-cn-north-1
DEBUG: Artifact key: stack-tools-non-production-main/73f8b3aef23a21519d0d4f88df0d83056de5b0d638492ec9fc3dcf4743176927
DEBUG: ChangeSet status: CREATE_PENDING
DEBUG: ChangeSet status: CREATE_IN_PROGRESS
DEBUG: ChangeSet status: CREATE_IN_PROGRESS
DEBUG: ChangeSet status: CREATE_IN_PROGRESS
DEBUG: ChangeSet status: CREATE_IN_PROGRESS
DEBUG: ChangeSet status: CREATE_COMPLETE
Deploying template 'main.yml' as stack 'stack-tools-non-production-main' in cn-north-1.
DEBUG: 
Stack stack-tools-non-production-main: UPDATE_COMPLETE
Successfully updated stack-tools-non-production-main