Allow delayed attribute evaluation. Add tests for delayed evaluation

Conflicts:
	lib/chef/mixin/params_validate.rb
More specs for more coverage on delayed evaluator usage
Rename #delay_eval helper to #lazy. Update specs to account for change.
Remove block parameter support from #set_or_return

Conflicts:
	lib/chef/mixin/params_validate.rb
Merge branch 'CHEF-3731-chef-11'