tools: notifier: Notification properties changes.

Before this change validation was done both in
NotificationService.initConfigurationProperties and in NotificationProperties
itself. all moved to  NotificationProperties.

The properties themself are not read from the notification service
to be instance variables inside the notifier but are read each time
they are needed.

Change-Id: I5753ba2cad2de90a7f2d14bd4675edc1dd35045e
Signed-off-by: Mooli Tayer <mtayer@redhat.com>