Support for AWS_PROFILE env var and shared configuration cred setup #14
Description
At the moment the CLI does not support the use of shared configuration credentials setup (https://github.com/aws/aws-sdk-go#configuring-credentials) and selecting the aws profile by using the standard AWS_PROFILE environment variable.
To make the shared config credentials, I just had to set up the environment variable "AWS_SDK_LOAD_CONFIG=1" and as per the documentation pass the parameter "--profile". Although I could use --profile $AWS_PROFILE to pass the profile, ideally I'd like for that to be implicit, like in the aws cli.