Add a workaround for Travis xenial permission issue.
Add a workaround for Travis xenial permission issue.

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