Update README.md

Update README.md

Added note that current stable repo is moq4

Refactored out IAspect.cs and made the default Behavior.cs actually be a CompositeBehavior.cs that runs multiple behaviors in phases (Before/After/Invoke).

Extracted IBehavior interface, and created DelegateBehavior to allow anonymous behaviors.

Extracted IAspect interface.

Add dynamic proxy to tests, for more realistic testing.

Add support for dynamically disabling aspects, and stopping pipeline behavior.

Added aspects to behaviors.

Refactored fake mock base implementation to TestMock. Fixed failing proxy tests.

Renamed IProxied.cs to IMock.cs, changed target namespace to Moq.Sdk

Added license headers to all files.

Create README.md

First pass on the proxy interception abstraction

Added initial v5 spike for historic purposes.