Add thread support

[sgedward]

#55

Change:
slack_comm.py

[mikegrima]

Hello @sgedward. Would prefer not making use of globals.

I think this would be best accomplished by having a function to return a timestamp, and having thread sent in via a keyword arg to the say* functions.

I think an approach similar to #63 would best implement this feature.

[sgedward]

@mikegrima thanks for leting me know. fixed

[mikegrima]

Testing this today

[mikegrima]

@sgedward slight merge conflict that should be very easy to fix.

[mikegrima]

I'll fix the conflict -- some changes I need to make to incorporate this PR with the ephemeral messages one.