Fix relationship set up (inspired by the rack-core-data project)
Add a `:nested_attributes` option to activate or note the sequel plugin
Merge branch 'support-nested-attributes' of github.com:dulaccc/rack-scaffold into dulaccc-support-nested-attributes

Conflicts:
	example/config.ru
	lib/rack/scaffold/adapters/core_data.rb
Merge branch 'master' of github.com:mattt/rack-scaffold