slovenian translation minor (typo) fix

[Miha Radej <miha(dot)radej(at)siix(dot)com>]

hi!

this is a minor translation fix as i found some typos.
zip file including the .po and .mo files can be found here:
http://mcajvar.prkoritu.net/pgadmin/sl_SI.zip (not attaching it because 
i had problems last time i tried).

--
regards,
M