add support for logind

I'm forwarding this commit by Rex Dieter to add logind support

http://pkgs.fedoraproject.org/cgit/cinnamon-session.git/commit/?h=f20&id=634587ebed44b43e6e081dc1a5a80d9152681159
more logind changes
Merge pull request #6 from leigh123linux/patch-2

add logind support