Move dependency fields in dependency_editor to a new partial.

In preparation for distinguishing between question_group dependencies
and question dependencies.
	new file:   app/views/dependencys/_dependency.html.erb
	modified:   app/views/dependencys/_form.html.erb
Get question_group based dependencies to behave correctly in Surveyor.

	modified:   app/controllers/dependencys_controller.rb - modified
	to use an instance variable @question_or_group that will take the value
	of either the question with the dependency or the question group with the dependency.
	This makes it possible to create or edit dependencies using nested attributes on
	either question or question_group.  Note that Dependency will requires a value for
	either question_id or question_group_id but not both, so building dependencies against
	the correct parent (Question or QuestionGroup) is necessary.

	modified:   app/models/permitted_params_decorator.rb - add dependency_attributes to
	whitelist for question_group, accounting for the has_one Dependency and corresponding
	nested_attributes.

	modified:   app/views/dependencys/_column.html.erb - modify partial so that it no longer
	has a direct reference to @question or @question_group.  Instead, looks at it's parent, Dependency
	to determine how to build collection.

	modified:   app/views/dependencys/_dependency.html.erb - modify to get correct nesting for
	dependencies built against both Question and QuestionGroup.

	modified:   app/views/dependencys/_dependency_condition_fields.html.erb - modify partial to work
	against both parents of Question and QuestionGroup.

	modified:   app/views/dependencys/_form.html.erb - Determine whether @question is part of a group,
	and, if so, build the dependency against a QuestionGroup instead of Question.

	modified:   lib/assets/javascripts/surveyor_gui/surveyor_gui.js - make event handling for dependencies
	less brittle by using a pattern match for ids (i.e. [id*=<...>]) instead of a starts with (i.e. [id^=<...>])

	new file:   lib/surveyor_gui/models/question_and_group_shared_methods.rb - pull out the controlling_question
	method from question_methods so that it can be used for both Question and QuestionGroup.  Also, modify
	it so that it picks up the last question when the dependency is against a group.  This is needed to get the
	question numbering right.

	modified:   lib/surveyor_gui/models/question_group_methods.rb - include QuestionAndGroupSharedMethods.

	modified:   lib/surveyor_gui/models/question_methods.rb - include QuestionAndGroupSharedMethods.

	modified:   surveyor_gui.gemspec - ditch the debugger.  Uncomment it in testbed when necessary.