Merge pull request #285 from noxhoej/master

Fix EasyNetQ.nuspec by adding the dependency on System.Collections.Immut...
Fix "NullReferenceException" when trying to get message from empty queue
fixed publishing messages after restoring connection to RabbitMQ
Merge pull request #286 from letalumil/master

Fix "NullReferenceException" when trying to get message from an empty queue
Merge pull request #287 from deadhu/master

fixed publishing messages after restoring connection to RabbitMQ
Fix for https://github.com/mikehadlow/EasyNetQ/issues/288, making DefaultConsumerErrorStrategy thread-safe.