Update st2common requirements.txt
Update st2common requirements.txt

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