Tests don't pass under ruby 2.1.2

[caryp]

/Users/cp/.rbenv/versions/2.1.2/bin/ruby -I/Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib:/Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-support-3.0.3/lib -S /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/exe/rspec spec/chef/knife/rightscale_server_create_spec.rb
/Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/formatters.rb:167:in `find_formatter': Formatter 's' unknown - maybe you meant 'documentation' or 'progress'?. (ArgumentError)
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/formatters.rb:126:in `add'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/configuration.rb:624:in `add_formatter'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `block in load_formatters_into'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `each'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `load_formatters_into'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:24:in `configure'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:96:in `setup'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:85:in `run'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:70:in `run'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:38:in `invoke'
  from /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/exe/rspec:4:in `<main>'
/Users/cp/.rbenv/versions/2.1.2/bin/ruby -I/Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/lib:/Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-support-3.0.3/lib -S /Users/cp/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rspec-core-3.0.3/exe/rspec spec/chef/knife/rightscale_server_create_spec.rb failed