use kaminari.gemspec database_cleaner in sub gemfiles

gemfiles/active_record_40.gemfile

@@ -3,6 +3,5 @@ source 'https://rubygems.org'
 gem 'railties', '>= 4.0.0'
 gem 'activerecord', '>= 4.0.0', :require => 'active_record'
 gem 'rspec-rails', '>= 2.0'
-gem 'database_cleaner', '>= 1.0.1'
 
 gemspec :path => '../'

gemfiles/active_record_edge.gemfile

@@ -7,6 +7,5 @@ git 'git://github.com/rails/rails.git' do
 end
 
 gem 'rspec-rails', '>= 2.0'
-gem 'database_cleaner', '>= 1.0.1'
 
 gemspec :path => '../'