Manage both suspension and hibernation

[almostearthling]

Hibernation and suspension issue different signals on the DBus (if they actually do). When should listen to both, possibly triggering the same tasks - that is, both events should make the same event-based condition True.

Note: to cause a conddition to be verified on more than one signal may require a redesign of stock events; however this should not impact compatibility across versions, as stock events are not retrieved from data files.

[almostearthling]

The problem described in comments for #83 is actually better explained in this issue.

[almostearthling]

A reference (although not specific to Ubuntu) here.