makefile: Make root requirement more clear

Change-Id: I2b5cdc910dba316417d1a2e2202e9347f90b2596
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
makefile: Add epel-release repository

epel-rlease yum repository is required for installing livecd-tools.

Change-Id: I3e9b2b2611498d5ab02dcf7c09ce31a540ff535d
Signed-off-by: Nir Soffer <nsoffer@redhat.com>