(From DCist contributor Kanishka Gangopadhyay) If you’re looking for something to do on this rainy weekend in D.C., you might think about putting on your finest hemp clothing and attending the DC Green Festival being held at the Washington convention center. A joint project of Global Exchange and Co-Op America, the Green Festivals are a two-day party with a serious purpose: to accelerate the emergence of a new economic paradigm that is life-affirming, inclusive and…