add metrics-rds.rb (#138)
add metrics-rds.rb (#138)

* add metrics-rds.rb

* change to aws-sdk-v2

* delete unused block

* fix rubocop

* delete def aws_config

* delete role and credentials

majormoses/sensu-plugins-aws,sstarcher/sensu-plugins-aws,obazoud/sensu-plugins-aws,sensu-plugins/sensu-plugins-aws,obazoud/sensu-plugins-aws,brendangibat/sensu-plugins-aws,nyxcharon/sensu-plugins-aws,nyxcharon/sensu-plugins-aws,majormoses/sensu-plugins-aws