only stem words we aren't skipping
only stem words we aren't skipping

Since code checks words and not keys against CORPUS_SKIP_WORDS it makes
sense that we can defer stemming and interning until after we've checked
that we will use the word.

sanbiv/classifier-reborn,jekyll/classifier-reborn,zuf/classifier,kreynolds/classifier-reborn,ybur-yug/classifier,MadBomber/classifier-reborn,MadBomber/classifier-reborn,sanbiv/classifier-reborn,jekyll/classifier-reborn,kreynolds/classifier-reborn