Add User when not present in local awscli config

[blakeca00]

if --user-name parameter is used to change keys for an IAM user not present in the local awscli config:

$ keyup --profile default --user-name developer1

keyup should create a new entry in the local awscli config and add the user

[blakeca00]

Event:

keyup --operation up:

Keyup Response:

if user exists in aws account && ! exist local awscli:
    add_user_local_config
elif exists in both:
    rotate_keys

[blakeca00]

SCOPE UPDATE:

For an IAM user which exists in an AWS Account (and allowable permissions), keyup will:

1. Request a new set of keys for the user
2. Add the user to the local awscli configuration with the new keys requested

Keys can then be rotated using keyup as normal