Support creating AWS profile named according to the AWS account alias / number

[nimrodkor]

We have a few AWS accounts in our org, and want to be able to assume role into each one of them. The name of the role is long when you use the --profile flag for every command, so we thought it would be easier to use just the account alias / number instead of the acc-role option which gives us a long result.

Expected Behavior

after setting the cred_profile parameter to acc, and the account alias is acme3:

$ gimme-aws-creds --profile acme
Saving arn:aws:iam::000000000000:role/dev as acme3
Written profile acme3 to /path/to/creds

Current Behavior

This isn't possible currently

Possible Solution

Add another option to this flag

PR incoming :)