core: Do not send group and name in notification responses

We already store a copy of the key in the client side of the API for
notifications, and no longer need to send the group and name in our
response messages.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
test: Update check_daemon to notification changes

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
Update client API to new notification changes

Notification responses are now stored in the first and only element
of our response list, as we now store the interested key in the client
side of the API.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
Update TODO

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>
demo: Do not segfault when key is not found

We now make our callback quite robust and handle various cases where
an operation may have failed (async), ensuring we do not crash just
because a key does not exist.

Signed-off-by: Michael Ikey Doherty <michael.i.doherty@intel.com>