PublishedMessageEvent, DeliveredMessageEvent

Here is an addition to already existed events. For instance it can be
usefull for client-side message tracking.
Fix EasyNetQ.nuspec by adding the dependency on System.Collections.Immutable.Net40
Bump the version
Merge pull request #284 from Pliner/producer-consumer-events

PublishedMessageEvent, DeliveredMessageEvent
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Source/Version.cs
Use ILRepack to internally merge  System.Collections.Immutable.Net40
Internalize ReadOnlyCollectionsInterfaces.dll as well, since it is a dependency of System.Collections.Immutable.Net40.dll
The internalization of ReadOnlyCollectionsInterfaces.dll apparently gives problems when used on a .net4.5 platform, so revert to dependencies.
Correct version text in Version.cs
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.
Bump version number in Version.cs
Use double-checked locking in DefaultConsumerErrorStrategy.Connect() for potential performance gain...
Added MessageCount method to AdvancedBus
Merge pull request #289 from noxhoej/master

Make DefaultConsumerErrorStrategy thread-safe
Bump version number in Version.cs