New development release of xfce4-power-manager.

This release marks the transition to several new
technologies.

* Port to Gtk3 (Eric, Simon)
* Port to gdbus (Peter)
* Drop LXDE panel plugin
* Bumped dependencies:
 - UPower>= 0.99
 - Gtk3 >= 3.14
 - libxfce4ui-2

* Miscellaneous improvements:
 - The settings dialog has been ported to GtkApplication
 - The panel plugin now uses UPower's icon names
   directly and is consequently compatible with all
   major icon themes out of the box
 - The panel plugin uses symbolic icons
 - The systray icon uses colored icons
 - The settings dialog now has a unique icon name
   (xfce4-power-manager-settings)

* And finally some bug fixes:
 - Fix for panel icon on Desktop systems (Bug #11840)
 - Never use symbolic icons for the systray (Bug #11756)
 - Look up the schema for light-locker's settings recursively (Bug #11488)
 - Don't crash when UPower returns  for the icon-name (Bug #11756)

* Translation updates:
Asturian, Chinese (China), Chinese (Taiwan), Czech,
French, German, Greek, Indonesian, Italian, Japanese,
Kazakh, Korean, Lithuanian, Malay, Norwegian Bokmål,
Polish, Portuguese, Portuguese (Brazilian), Russian,
Serbian, Slovak, Slovenian, Spanish, Swedish, Thai,
Ukrainian.