install-deps.sh,deb,rpm: move python-saml deps into debian/control and ceph.spec.in

install-deps.sh,deb,rpm: move python-saml deps into debian/control and ceph.spec.in

these dependencies are only used for building python-saml which is in
turn used for the SAML support. this feature is tested using
`test_sso.py` while performing dashboard tests. we do not package or
ship python-saml along with other Ceph packages. so let's move these
dependencies to the "make check" sections in ceph.spec.in and
debian/control for simplifying install-deps.sh.

Signed-off-by: Kefu Chai <kchai@redhat.com>