Rename host-based auth to identity-based auth

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Whitespace fixes

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Update cert-based auth docs to use new options

Signed-off-by: Ben Firshman <ben@firshman.co.uk>