Use profiles when selecting credentials from ~/.aws/credentials

[leedm777]

AWS tooling which reads credentials from ~/.aws/credentials also supports profile selection. This allows folks with multiple AWS accounts to select which account credentials they wish to use for particular tasks. This is usually specified by either configuration, with with the AWS_PROFILE or AWS_DEFAULT_PROFILE environment variables.

See http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html#cli-multiple-profiles

re: distribution/distribution#1041

[0xmohit]

This appears to have been fixed in 6770071.