I18n: Update translation ru (100%).

217 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation sr (100%).

217 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
port xfpm to libupower-glib / add support for upower-0.99.0 API

* port most of the upower interfaces to upower-glib
* conditionalize stuff that has been deprecated in upower >= 0.99.0
* suspend / hibernate is handled by systemd/logind
* if upower is >= 0.99.0 and logind is not running, log errors
  (as functionality will be missing)

Signed-off-by: Eric Koegel <eric.koegel@gmail.com>
get rid of XfpmDeviceState and XfpmDeviceType

They are only mirroring UpDeviceState and UpDeviceKind
from libupower-glib anyway.

Signed-off-by: Eric Koegel <eric.koegel@gmail.com>
xfpm_backlight_button_pressed_cb: fix popup display

With /xfce4-power-manager/change-brightness-on-key-events=false, the
level variable is used uninitialized and the popup's level gauge is
wrong. Slight Code reformatting included, to avoid duplicating most
of the code.  (Rebased version of a patch I wrote a year ago)

Signed-off-by: Eric Koegel <eric.koegel@gmail.com>
Fix potential uninitialized variable