Added code to specify which columns in weight_data are accessible to Ruby.
Also, set up a minimum WeightDataController.

 On branch experimental
 Changes to be committed:
	new file:   app/assets/javascripts/weight_data.js.coffee
	new file:   app/assets/stylesheets/weight_data.css.scss
	new file:   app/controllers/weight_data_controller.rb
	new file:   app/helpers/weight_data_helper.rb
	modified:   app/models/weight_data.rb
	new file:   test/controllers/weight_data_controller_test.rb
	new file:   test/helpers/weight_data_helper_test.rb