Require minimum RSpec version for new syntax

Author: avit

ice_cube.gemspec

@@ -18,5 +18,5 @@ Gem::Specification.new do |s|
   s.rubyforge_project = "ice-cube"
 
   s.add_development_dependency('rake')
-  s.add_development_dependency('rspec')
+  s.add_development_dependency('rspec', '> 3')
 end