Adding a project to show how mentions works

[Virtual-Josh]

This is a sample project to show how mentions works within Teams. This also removes the code about mentions from the Roster project.

[EricDahlvang]

I think we are excluding the .zip of the manifest. We might need ro remove it from other projects too?

[johnataylor]

i think we don't need to check in the manifest zip files. we should probably go through and get rid of them all. but not a big deal right now - we have checked them in all over the place.

[johnataylor]

i think it's nice to have this sample - at least it's going to help the docs.

[fuselabs]

✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.AI.Luis.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.AI.QnA.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.ApplicationInsights.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.Azure.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.Dialogs.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.TemplateManager.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Configuration.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Connector.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Schema.dll compared against version 4.3.1

[coveralls]

Pull Request Test Coverage Report for Build 79600

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 81.26%

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Totals
Change from base Build 79583:	0.0%
Covered Lines:	3599
Relevant Lines:	4429

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💛 - Coveralls

[fuselabs]

✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.AI.Luis.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.AI.QnA.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.ApplicationInsights.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.Azure.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.Dialogs.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Builder.TemplateManager.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Configuration.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Connector.dll compared against version 4.3.1
✔️ No Binary Compatibility issues for Microsoft.Bot.Schema.dll compared against version 4.3.1

looks like Josh has resolved this