Update rubygems dependency to ~>1.4

* This gem depends on test-unit, which depends on hoe, which depends on
  rubygems >= 1.4. I added this dependency to make it more clear
  up-front that rubygems ~>1.4 is required for this gem to install.

Rakefile

@@ -14,6 +14,8 @@ begin
     gem.authors     = [ 'Martin Gamsjaeger (snusnu)' ]
     gem.has_rdoc    = 'yard'
 
+    gem.required_rubygems_version = '~> 1.4'
+
     gem.rubyforge_project = 'datamapper'
   end
 

dm-active_model.gemspec

@@ -7,9 +7,9 @@ Gem::Specification.new do |s|
   s.name = %q{dm-active_model}
   s.version = "1.1.0.rc2"
 
-  s.required_rubygems_version = Gem::Requirement.new("> 1.3.1") if s.respond_to? :required_rubygems_version=
+  s.required_rubygems_version = Gem::Requirement.new("~> 1.4") if s.respond_to? :required_rubygems_version=
   s.authors = ["Martin Gamsjaeger (snusnu)"]
-  s.date = %q{2011-03-01}
+  s.date = %q{2011-03-05}
   s.description = %q{A datamapper plugin for active_model compliance and thus rails 3 compatibility.}
   s.email = %q{gamsnjaga [a] gmail [d] com}
   s.extra_rdoc_files = [