Add tag to tasks that install RPMs

[steven-schattenberg-itential]

There are cases where we need to install RPMs manually, e.g. when a customer does not have access to a particular Yum repo. In these cases, it would be nice if the playbooks had tags for the tasks that perform anything related to installing from Yum (Repo keys, RPM installs, etc). That way we can run the playbooks and use --skip-tags.