Support new XDG thumbnail directory locations

https://bugzilla.gnome.org/show_bug.cgi?id=675166
power: Don't leak notifications

https://bugzilla.gnome.org/show_bug.cgi?id=673978
mouse: Add more debug for syndaemon launch
power: Avoid duplicate translations

It confuses our tools if we have the same msgid both in
gettext() and ngettext(), so be a bit more clever here.
Bonus: save 40 lines of code.

https://bugzilla.gnome.org/show_bug.cgi?id=669732
keyboard: Don't crash if LANG is empty

Use en_US as the fallback locale if LANG isn't set.

https://bugzilla.gnome.org/show_bug.cgi?id=678100
keyboard: Don't crash on invalid LANG
wacom: Use GnomeRROutput not GnomeRROutputInfo

GnomeRROutputInfo is an expression of the dumped config file,
not anything useful to poke at the current display configuration.

https://bugzilla.gnome.org/show_bug.cgi?id=677032
power: Include the correct header
common: Add systemd power state helpers

Add systemd helpers to replace ConsoleKit shutdown, and upower
hibernation and suspend.

https://bugzilla.gnome.org/show_bug.cgi?id=677241
power: Add missing dependency on libnotify
power: Add test application
power: Use new power state helpers

https://bugzilla.gnome.org/show_bug.cgi?id=677241
media-keys: Use new power state helpers

https://bugzilla.gnome.org/show_bug.cgi?id=677241
build: Add definition of CONSOLEKIT_* in new location
build: Delete unused defines
build: Link test-power plugin against -lm, it uses floor()

https://bugzilla.gnome.org/show_bug.cgi?id=678120
Don't pass NULL where a dialog is expected

...it leads to crash. Seen in
https://bugzilla.redhat.com/show_bug.cgi?id=831666

https://bugzilla.gnome.org/show_bug.cgi?id=678133
power: Remove use of empty KEYRING_* variables
daemon: Remove unused UPOWER_* variables
power: Link against xext, needed for XSync API

https://bugzilla.gnome.org/show_bug.cgi?id=678120