updated gitignore to ignore OS level .DS_Store files
updated gitignore to ignore OS level .DS_Store files

wso2/wso2-qa-artifacts,pubudup/wso2-qa-artifacts,pubudup/wso2-qa-artifacts,wso2/wso2-qa-artifacts,wso2/wso2-qa-artifacts,pubudup/wso2-qa-artifacts,pubudup/wso2-qa-artifacts,pubudup/wso2-qa-artifacts,wso2/wso2-qa-artifacts,wso2/wso2-qa-artifacts,wso2/wso2-qa-artifacts