fix(slack): use conversations api

[wass3r]

❤ THANKS FOR HELPING OUT :D

Proposed change

This addresses and issue with populating channel information reliably. Now uses Conversations API and probably solves #46 (at least in part).

Types of changes

What types of changes is this pull request introducing to flottbot? Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

You can fill this out after creating your PR. Put an x in the boxes that apply

• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[coveralls]

Pull Request Test Coverage Report for Build d1cd816fe34e69a17b583a631a349dc0aaa8235f-PR-131

• 0 of 45 (0.0%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.4%) to 37.578%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
remote/slack/helper.go	0	45	0.0%

Files with Coverage Reduction	New Missed Lines	%
remote/slack/helper.go	2	0%

Totals
Change from base Build 8086b00285376c6f07066ce1aed68aebadc1cdfd:	-0.4%
Covered Lines:	838
Relevant Lines:	2230

---

💛 - Coveralls

[sjqnn]

All of the example rules that I tried appeared to work fine still, DMs work fine, I see the debug messages now coming through for unhandled event types. Anything else you'd like me to try as a test @wass3r ? Otherwise LGTM 👍

[wass3r]

Excellent, no, I think that's it. Thanks for giving it a whirl.