Revert "Remove py3 check from Travis."
Revert "Remove py3 check from Travis."

This reverts commit 660eca4774f4280ebbd266096d04a1c6cc0158c9.

nzlosh/st2,nzlosh/st2,Plexxi/st2,Plexxi/st2,StackStorm/st2,nzlosh/st2,Plexxi/st2,Plexxi/st2,StackStorm/st2,StackStorm/st2,StackStorm/st2,nzlosh/st2