The butler doesn't like shared channels!

[mattvv]

Describe the bug
The butler seems to only support guests of the same house!
We tried using it in a shared channel and it seems like it messages the people who are not 'shared' ie/ on the other side.

To Reproduce

1. Add the butler to either side or both sides of a shared channel.
2. Say how about '4pm'
3. Users who are on the 'shared' slack other side don't see the butlers message.

Expected behavior
A message should be sent to all users in the shared channel.

Additional context
We tried having two butlers, and just one butler.