fix systemd-login1 support for hibernate/suspend
Remove autogenerated file
Make upower optional

This commit is just an improved version of the pull request by Wolfgang Ulbrich
at https://github.com/mate-desktop/mate-session-manager/pull/38
making it working with both upower and systemd, and improving configure part
Systemd support: session_id is char*, not int
Fix g_type_init deprecation
Fix return value in void functions
Remove disto dir