support old rubygems versions

aasm.gemspec

@@ -10,6 +10,7 @@ Gem::Specification.new do |s|
   s.homepage    = %q{http://rubyist.github.com/aasm/}
   s.summary     = %q{State machine mixin for Ruby objects}
   s.description = %q{AASM is a continuation of the acts as state machine rails plugin, built for plain Ruby objects.}
+  s.date        = Time.now
 
   s.add_dependency             'activerecord'
   s.add_development_dependency 'rake'