Build python api manpage conditionally

Related to #100.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Michal Toman <mtoman@redhat.com>
spec: don't build satyr-python manpage on el6

Related to #100.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Michal Toman <mtoman@redhat.com>