* Change 'spec' Rake task to 'spec:unit'
* Require unit_spec_helper.rb in unit tests, not spec_helper.rb
* Re-namespace files in spec/support/unit under UnitTests
* Files in spec/support/unit/helpers no longer automatically add
themselves to RSpec - this happens in unit_spec_helper.rb
* Extract RecordWithDifferentErrorAttributeBuilder and
RecordValidatingConfirmationBuilder to separate files
* Move spec/shoulda to spec/unit_tests/shoulda
* Move spec/support/*.rb to spec/support/unit_tests/{helpers,matchers}
* Move spec_helper.rb to unit_spec_helper.rb
Alejandro Gutiérrez