Skip test_that_tags_can_have_dashes_and_underscores for RDiscount 2.0.7.x series.
Skip test_that_tags_can_have_dashes_and_underscores for RDiscount 2.0.7.x series.

liangsun/discount,liangsun/rdiscount,liangsun/discount,liangsun/discount,liangsun/rdiscount,liangsun/rdiscount,liangsun/discount,liangsun/rdiscount,liangsun/discount