Add more test cases for stream endpoint which verify that the st2.chatops__anouncement event is indeed received and not filtered out.
Add more test cases for stream endpoint which verify that the
st2.chatops__anouncement event is indeed received and not filtered out.

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