increase max length for badge description in OBI spec

[davelester]

Correct me if I'm wrong, but it appears that the OBI specification requires a badge description to be a maximum of 128 characters. Can we increase this, since it's likely that badge descriptions will usually be longer than a tweet?

[brianloveswords]

I think we should probably have a discussion about this. I think the description should stay as pithy as possible and any further explanation belongs at the criteria level. I'm open to debate on this, though.