Expose Success outcome on SendEmail activity (elsa-workflows#3426)

Fixes elsa-workflows#3425

Add version endpoint for consumption by dashboard (elsa-workflows#3389)

Closes elsa-workflows#3370

Apply nuget API key to correct provider

Update NuGet API key and regex

Mark sample project as unpackable

Fix version number on dashboard for 2.8

Retry build for 2.8

Update version on dashboard home page

Update Elsa.Samples.CompensationConsole.csproj

Update appveyor.yml