Bump version to 1.6.17
Add release notes for 1.6.16
Bump version to 1.6.15, add release notes
Bump version to 1.6.14
Update release notes for 1.6.13
Add release notes for 1.6.12
Fix NullReferenceException when User is null for ASP.NET Core also
Merge branch 'master' of https://github.com/HangfireIO/Hangfire
Add release notes for 1.6.9
Bump version to 1.6.8, add release notes