notifier: use LocalConfig as configuration file

gives the advantage of defaults and conf.d structure.

Change-Id: Iea3d8a9887d76920c51d26467c634912e64242dd
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>
notifier: remove NotificationConfigurator as superseded by LocalConfig

cleanup validations of parameters to be acquired the LocalConfig way.

move most of validation to main function in more structural manner.

Change-Id: I9f8ebea59fabac945b95b6422d1bfbf8a2b1d208
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>