Revert "Upgrade ruby from 2.1.2 to 2.1.5 again."

This reverts commit 571163fe3e66fe3d05ae7fdbd85762f06fe640c7.
Updated gems simple_form, bcrypt, bootstrap-sass, devise, factory_girl, factory_girl_rails, mysql2, puma, rails-footnotes, rails_layout, sprockets-rails, sprockets, whenever.