[css-counter-styles] Ethiopian numbering

Since I ran into some Ethiopians this weekend, I decided to interrogate
them on list numbering and punctuation. Here's what I was told:

   * We shouldn't expect Ethiopians to agree on any kind of convention.
     We have to just pick something reasonable.
   * Using ASCII period as a suffix is clearly wrong, since it is not a
     punctuation character they use. Better to use just a space.

~fantasai