1. Add new option 'use_barbican' in config file [vim_keys] section,
default value is False for Pike.
2. Use fernet to encrypt vim password, and save the fernet key into
barbican as a secret.
3. Add new fields 'key_type', 'secret_uuid' into VimAuth.auth_cred
json string. secret_uuid is masked in vim-show or vim-list response.
4. Set the vim's default 'shared' value to False,
vim can only be used by who created it.
5. Add a devref to show how to test.
6. Add a release note.
Implements: blueprint encryption-with-barbican
Partial-bug: #1667652
Change-Id: I5c779041df5a08a361b9aaefac7d241369732551
07428d4985