Windows manager should be independent on session manager, especially when we
have multiple session manager like mini-x and matchbox session.
This commit remove session-manager stuff in matchbox-wm, as matchbox-session
already has duplicated code. Also adjust alternative priority for mini-X to
make it higher priority over matchbox-session.
Signed-off-by: Zhai Edwin <edwin.zhai@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
