added tests/README giving basic test instructions
added tests/README giving basic test instructions

cjlee112/pygr,ctb/pygr,cjlee112/pygr,GenDataPro/pygr,GenDataPro/pygr,theoryno3/pygr,ctb/pygr,RitwikGupta/pygr,RitwikGupta/pygr,theoryno3/pygr,RitwikGupta/pygr,ctb/pygr,cjlee112/pygr,ctb/pygr,GenDataPro/pygr,ctb/pygr,cjlee112/pygr,theoryno3/pygr