Skip 3694 warnings on trivial resource cloning

Turns the 3694 warning into a debug message if the prior resource is
identical to the current resource.  Suggestion for opscode/chef-rfc#76
All three affect **only** `non-use_inline_resources` LWRPs:

`:@elapsed_time`: this will be updated when the same resource has been called outside the LWRP.
`:@enclosing_provider`: This value will be different for all LWRP resources.
`:@params`: This [is set to nil](https://github.com/opscode/chef/blob/master/lib/chef/dsl/recipe.rb#L114-L116) because [the `@params` attribute does not exist](https://github.com/opscode/chef/blob/master/lib/chef/provider.rb#L55-L78) in providers, in all other cases [it will be `{}`](https://github.com/opscode/chef/blob/master/lib/chef/recipe.rb#L71). This can be considered a bug, but it does not hurt to add it. The `@params` attribute is not used at all in resources. It's for definitions.

That said, wait for my next comment before changing anything. I just realized something else.