fix(subscription): Fix handling of Close()

Do not call sysconn.Close outside of dbus.go. The behavior is surprising
and depending on how the error happened sysconn could already be closed,
resulting in a double-close panic.

Gracefully exit the signal goroutine if its channel has been closed.
Merge pull request #44 from marineam/close

fix(subscription): Fix handling of Close()
feat(login1): initial login1 interface

This is an initial login1 binding that only supports the Reboot() call.
It would be great to write a generator for this.
Merge pull request #45 from philips/login1

feat(login1): initial login1 interface
feat(dbus): Initial support for systemd in user session mode.

This is just the basic piece to connect to the session bus and
optionally use that in tests instead of the system bus. Tests assuming
they are operating on the system instance still need to be fixed.