The NotificationService (base class for SlackService, HipchatService ...) has both dynamic
cluster settings and SecureSettings and builds the clients (Account) that are used to comm
with external services. This commit fixes an important bug about updating/reloading any
of these settings (both Secure and dynamic cluster). Briefly the bug is due to the fact that
both the secure settings as well as the dynamic node scoped ones can be updated
independently, but when constructing the clients some of the settings might not be visible.
04ee05f199