Increase version to 2.4.0

Increase version to 2.3.0

Add netstandard2.0 target

Update version to 2.1.7

Update version to 2.1.7

Update version to 2.1.6

Update version to 2.1.5

Reduce allocations on list deserialization (Azure#310)

* Do not capture context on async awaits

* Do not capture context on async awaits (2)

* Improve list allocation when deserializing lists from messages

* Fixed List implementation with initial capacity

* Fixed list implementation for NETMF

[Azure#276] ReceiverLink receive timeout issue

Test: add a delay to allow messages to be completely released.