libxklavier: version bump to 5.0

[Sergey Udaltsov <sergey udaltsov gmail com>]

Hi ppl

I request permission to bump the required libxklavier version to 5.0
on wiki page. The library API was changed to facilitate latest changes
in gnome-settings-daemon and gnome-applets - i.e. phasing out of the
indicator applet, and using notification icon (implemented in g-s-d
keyboard plugin).

Any objections?

Sergey