Correctly get session path
Correctly get session path

The old way of getting the session path was to simply append the session id to
the path "/org/freedesktop/login1/session/". However this is not the correct
path for newer systems like Fedora 26.

Instead, get the session path directly from the session manager from the id via
a dbus call to GetSession().

fixes #35

ascent12/wlroots,ascent12/wlroots,swaywm/wlroots,SirCmpwn/wlroots,swaywm/wlroots