puppetlabs_spec_helper: Allow 3.x

this was tested in voxpupuli/puppet-ferm#130

Author: bastelfreak

moduleroot/Gemfile.erb

@@ -29,7 +29,7 @@ group <%= group %> do
 end
 
 <% end -%>
-gem 'puppetlabs_spec_helper', '~> 2.0', :require => false
+gem 'puppetlabs_spec_helper', '>= 2', '< 4', :require => false
 gem 'rake', :require => false
 gem 'facter', ENV['FACTER_GEM_VERSION'], :require => false, :groups => [:test]