Set Slack parameter AsUser to true

[tmcevoy14]

Set as_user to true for slack post message function so messages to a Slack channel use the bot's name and icon.

[lkysow]

Thanks for the PR. Can you show me a screenshot so I can understand the difference between the old and new way.

[tmcevoy14]

Sure @lkysow. Without this flag set, the bot's configurations in Slack do not appear in the message sent from Atlantis'.

Seting the as_user flag to true ensures that the name and profile picture are used for postMessages. So instead of "Bot" the message would appear as a specific bot that I created, e.g. "AtlantisBot".

[lkysow]

Do you have a screenshot for what it looks like on?

[tmcevoy14]

Yep, this is a screenshot after compiling it locally and testing:

[codecov]

Codecov Report

Merging #907 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #907      +/-   ##
==========================================
+ Coverage   71.73%   71.74%   +<.01%     
==========================================
  Files          65       65              
  Lines        5283     5284       +1     
==========================================
+ Hits         3790     3791       +1     
  Misses       1199     1199              
  Partials      294      294

Impacted Files	Coverage Δ
server/events/webhooks/slack_client.go	96.36% <100%> (+0.06%)	⬆️

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[lkysow]

🎉 nice work! This will be in the next release.