add support for loading config through env vars
add security_token to config
update list to support reading config from env
update list to support reading from env vars
update attributes command for env var config support
update clone to read config from env vars
update create to read config from env vars
update deploy to read config from env vars
update destroy to read config from env vars
update events to read config from env vars
update execute to read config from env vars
update instances to read config from env vars
update outputs to read config from env vars
update parameters to read config from env vars
update protect to read config from env vars
update resources to read config from env vars
update status to read config from env vars
update template to read config from env vars
update update to read config from env vars
update cfn lib to use temporary credentials if present