node.recipe? was removed, no easy way to check for included recipes

node.recipe? method was removed, but no decent alternative is present. node[:recipes] include only recipes from the run_list, so in order to check for loaded recipes (e.g. by include_recipe) one must revert to using run_state.

Original ticket (CHEF-232)
When writing interdependent recipes, it would be good to easily determine if a recipe has been seen, via include_recipe, so behavior can be changed easily depending on the other recipes used.

Currently, this could work:

node.run_state[:seen_recipes].has_key?('some_recipe')

But that's rather cumbersome. This would be cleaner:

node.recipe?('some_recipe')