Ok, here is the updated version.  I rewrote it in the way to work
out-of-box for most (with single battery) users.
Checked it works fine with no D-Bus compiled in.  Or with disabled "upowerd"

Few users on different laptops tried this code and it works out-of-box for
them.

I did not documented power_supply interface, English is not my native
language, somebody could do it much better.  Also I have no knowledge at
all about power_supply interface.

Thanks

-- 
lg