Implement configuration options for acts_as_relation. The first option is whether all models should join with its superclass automatically.

Conflicts:
	acts_as_relation.gemspec
	lib/active_record/acts_as_relation.rb
	lib/acts_as_relation.rb
Use . for class accesses.

Conflicts:
	lib/active_record/acts_as_relation.rb

Conflicts:
	lib/active_record/acts_as_relation.rb
Fix reflection upon the derived class. The superclass relations should be there.

Conflicts:
	lib/active_record/acts_as_relation.rb

Conflicts:
	lib/active_record/acts_as_relation/access_methods.rb
Actually apply the forwarding.

Conflicts:
	lib/active_record/acts_as_relation.rb

Conflicts:
	lib/active_record/acts_as_relation/acts_as_modules.rb
Clean up code after upstream refactor.
Implement column_for_attribute for compatibility with simple_form

Conflicts:
	lib/active_record/acts_as_relation/acts_as_modules.rb
Fix wrong variable reference.

Conflicts:
	lib/active_record/acts_as_relation/acts_as_modules.rb
Combine both fixes for reflection into one branch.
Merge remote-tracking branch 'remotes/origin/lowjoel-implement-config'
Merge remote-tracking branch 'remotes/origin/lowjoel-fix-reflections'