packaging: setup: adding jboss.cer to the list of file to uninstall

Adding jboss.cer to the list of file to uninstall:
jboss.cer is actually created by engine-setup but is not
removed by engine-cleanup

Change-Id: I5cf8300b7b0b5030856e7e3b2a0c5d6a9dc009c0
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>