Bug#813094: Split braille support into a separate package

[Till Kamppeter]

I think this is a good idea. It makes one of the two utility packages be 
installed if at least one is available (ex: Ubuntu with only Main) and 
does not error if none is available. And it prefers the better if both 
are available (Debian and Ubuntu with Main and Universe).

Let us go this way.
   Till