Merge pull request #314 from chinaboard/master

SendAsync method
An attempt to fix #321
bump version
Merge pull request #323 from Pliner/#321

An attempt to fix #321
Tests.Perfomance.Produces failed to start

heartbeat -> requestedHeartbeat
Merge pull request #324 from Pliner/master

Tests.Perfomance.Produces failed to start
Removed Immutable Packages and replaced IEventBus.cs with previous version to prevent cs1685 compiler warnings
Version update to 0.39.2
Merge pull request #325 from Kempe/master

Removed Immutable Packages and replaced IEventBus.cs ...
SendAsync should return Task