Currently we restart all swift services regardless of the config file
being updated. This is very redundant, because some config files affect
only specific services (eg. account-server.conf is used only by
account-* daemons).
This introduces new "sub" tags such as swift-account-service and limit
the services being restarted.
Change-Id: Idfa09b63d291b0f71686554cb7c7b0597cb8842c