Add OnBeforeInvoke and OnAfterInvoke events

Support for hooking into service calls. Separate
events can be configured that will be fired before
and after the service method has been called.
Add comments to DynamicProxyTypeGenerator

Add some helpful comments that make reading the IL code
generation source a bit code easier.
Add method name and parameters to OnInvoke events

Modifies the proxy IL generator to report the
method name and parameters it was called with.
Add service method return value to OnAfterInvoke

Service method return value is now passed in the
event arguments when using OnAfterInvoke.
Mention OnBeforeInvoke and OnAfterInvoke in the readme
Fix typos in the readme regarding OnBeforeInvoke and OnAfterInvoke
Fix OnBeforeInvoke/OnAfterInvoke typos in readme
Merge pull request #3 from varkkjuh/oninvoke

Added OnBeforeInvoke and OnAfterInvoke event handlers