Update ruby to 2.1
Update rails to 4.1 beta
Use update instead of deprecated update_attributes
Update requires in application.rb to rails 4.1
Use rubygems version of rails_admin

Rails_admin gem was recently updated with
necessary changes from master.
Update gems
Update to rails 4.1 conventions
Fix ruby 2.1 Fixnum.ago deprecation warning
Add support for spring and zeus

Spring is enabled by default. Zeus can be enabled
by removing spring from gemfile and adding zeus.
Fix typo in cancan ability.rb
Update simple_form
Update rails_admin
Update readme