Use redhat-lsb instead of redhat-lsb-core.

The redhat-lsb-core package won't apparently be split out until RHEL
6.4 at the earliest:

    https://bugzilla.redhat.com/show_bug.cgi?id=835919

Change-Id: I4bc9bb542e68db26744b834a6de7d99b2249c568
Reviewed-on: https://review.openstack.org/23124
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins