Mostly cleanup of the codebase as preparatory work for the v6 client implementation

• Code cleanup:
  • Removed useless overloads and members in FakeModel.
  • Refactored Unit Tests (split IModel tests into several classes, got rid of the Arrange, Act and Assert comments, renamed methods) + added a few ones.
• No-op implementation if IModel.TxSelect, IModel.TxCommit and IModel.TxRollback instead of throwing.
• Implemented IModel.MessageCount(queue) and IModel.ConsumerCount(queue) based on QueueDeclarePassive.
• IModel.QueuePurge now returns the number of purged messages.

This release merges the PR by @inbarbarkai. They are one year-old, and I'm ashamed it took me this long to merge them. Because I'm now watching the repository, I should need less time to react in the future...
Once again thanks for his contribution.

• BUGFIX: #30. QueueDeclarePassive now throws if the queue does not exist. Similarly, ExchangeDeclarePassive throws if the exchange does not exist.
• FEATURE: #29. Support for the Alternate Exchange Feature.
• BUGFIX: #28. DefaultBasicConsumer.IsRunning property is now correctly returning true/false.

BUGFIX: #27. It was impossible to create a connection after having created and closed a previous connection.

BUGFIX: #25. Now it is possible to close a Channel after its connection was closed without the Channel.Close method throwing (this is consistent with how RabbitMQ.Client behaves).

Most of the work in this release was contributed by @inbarbarkai. Thanks to him!

• As suggested by @inbarbarkai: Basic support for IModel.ConfirmSelect and the IModel.WaitForConfirms* family.
• Support for IModel.CreateBasicPublishBatch was added thanks to PR #21 by @inbarbarkai.
• Consumers that implement both IBasicConsumer and IAsyncBasicConsumer are correctly handled by IModel.BasicConsume and IModel.BasicCancel thanks to PR #23 by @inbarbarkai.

• Package (and assembly) name changed from AddUp.RabbitMQ.Fakes to AddUp.FakeRabbitMQ.
• Symbols package is now a snupkg

This version fixes a rather nasty bug. It is recommended you update from v1.2.1 to this one!

The Nuget package is also available here: https://www.nuget.org/packages/AddUp.RabbitMQ.Fakes/1.2.2

The Nuget package is also available here: https://www.nuget.org/packages/AddUp.RabbitMQ.Fakes/1.2.1

First public version