Add PYPY to travis testing
Add PYPY to travis testing

knowsis/pika,vitaly-krugl/pika,jstnlef/pika,pika/pika,skftn/pika,hugoxia/pika,benjamin9999/pika,shinji-s/pika,zixiliuyue/pika,Tarsbot/pika,reddec/pika,vrtsystems/pika,Zephor5/pika