Fixed ajax nesting responses within #box instead of fully replacing contents

Visual effect of this bug was to have multiple shadows at the bottom of the
survey editor.

	modified:   lib/assets/javascripts/surveyor_gui/surveyor_gui.js
Added dropdown to the list of question types.

	app/controllers/questions_controller.rb: account for answer display
	order being nil.

	app/views/questions/_form.html.erb: added dropdown list to question
	type pulldown.

	app/views/surveyforms/_question_fields.html.erb: add dropdown
	question display.

	lib/assets/javascripts/surveyor_gui/surveyor_gui.js: account for
	dropdown in show_answers.

	lib/assets/stylesheets/surveyor_gui.sass: formatting for dropdown.

	lib/surveyor_gui/models/question_methods.rb: