gem: required rails >= 3.2.0
Change to automatic loading of modules
Define ActiveRecord::Base#<attribute>_was method
Add utusemi methods to ActiveRecord class.
Implemented times options for utusemi method
Fix ActiveRecord::Base#changed method
Update gemfiles
gem: Add rspec-rails and factory_girl_rails
rspec: Add files for spec
rake: Add default task
gem: Add rubocop
rubocop: double-quoted => single-quoted
rubocop: Refactor by rubocop
rake: Add rubocop into default task
rubocop: Refactor enable method in utusemi.rb
rubocop: Refactor build_where method in core.rb
rubocop: Refactor define_utusemi_association_reader method in core.rb
Add files for Travis-CI