Properly label a dependent group question on surveyform

Dependent question_groups have a direct association with
dependencies.  Methods to display the dependencies should
use the question_group has dependency relationship rather than
question has dependency relationship.  Modify surveyform accordingly.
	modified:   app/helpers/surveyform_helper.rb - pass a model object
	rather than builder object to list_dependencies.

	modified:   app/views/surveyforms/_question_group.html.erb - pass
	question rather than builder to list_dependencies.

	modified:   app/views/surveyforms/_question_wrapper.html.erb - pass
	question_group rather than builder to list_dependencies.

	modified:   lib/surveyor_gui/models/question_group_methods.rb -
	add controlling_questions method.