Add ability to sync creds back on modification
If enabled and if the client requests it, the server will check if new
credentials are available and send back a fresh copy to the client if they
are.
Works only if:
- allow_client_ccache_sync is True
- a custom ccache is not set for the service
- the client explicitly requests a sync for the call
Signed-off-by: Simo Sorce <simo@redhat.com>
[rharwood@redhat.com: Style fixes, typo in comment, commit message tweak]
Reviewed-by: Robbie Harwood <rharwood@redhat.com>