v3.0.0

• Profile is no longer passed to new process
• Exec process now gets AWS_VAULT={profilename} set and fails on the presence of this env.
• Exec defaults to using env vars for credentials, opt-in to metadata server via --server
• New server command runs a background server that exposes credentials from exec directly via 169.254.169.254:80. No more http_proxy.
• The source_profile is used for the cached session, making for better re-use of sessions across role heavy configs