Install rspec
Update to Rails 4.1.0.beta1 and install Spring
Rails 4.1 compat: Do not try to mutate AR Relation

http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#mutator-methods-called-on-relation
bundle exec spring binstub --all

Note: The daemon does not work properly with spring.
Do not use bin/rake to start it.
Use guard for running rspec
Get guard-rspec and rspec-rails versions compatible with Rails 4.1

https://github.com/rspec/rspec-rails/blob/master/Changelog.md#2990beta1--2013-11-07