warn about max_active_keys fernet keys

[AlvaroVega]

From @cesarjorgemartinez

Receipt and Token fernet key directories are the same but `max_active_keys` is different. Receipt `max_active_keys` will be ignored in favor of Token `max_active_keys`

[cesarjorgemartinez]

You need to set equal (6 is better value), for:

[fernet_receipts]
max_active_keys = 6

And

[fernet_tokens]
max_active_keys = 6

[AlvaroVega]

Then the fix will be add these commands to startup scripts:

openstack-config --set /etc/keystone/keystone.conf \
                 fernet_receipts max_active_keys 6 

openstack-config --set /etc/keystone/keystone.conf \
                 fernet_tokens max_active_keys 6 

[cesarjorgemartinez]

Yes, and I think it is not worth customizing it as a parameter, what do you think?