Belarusian 4 plural forms

[Albert Astals Cid]

> >All the language files for a given translation have to use the same number
> >of plural forms. Will you update all the existing Belarusian files to use
> >4 plural forms?
> 
> Of course.

I have changed all the files now the the nplurals=4 definition you used.

I'm still honestly not convinced it is needed, but you're the one doing the 
work after all, so worst case scenario you're translating one more form that 
isn't needed.

Cheers,
  Albert