With the addition of encrypted credential in keystone, we need to be able to
add setup steps in devstack to configure the credential repository with
encryption keys.
Depends-On: I97e7701bc5b8765d207cc721793643bcefa2d4e2
Depends-On: Id3e8922adc154cfec5f7a36613e22eb0b49eeffe
Change-Id: I433da9a257daa21ec3b5996b2bca571211f1fbba