Add railtie.rb to the plugin generator

[ttanimichi]

Before

$ rails plugin new myplugin
$ ls myplugin/lib/myplugin
version.rb

After

$ rails plugin new myplugin
$ ls myplugin/lib/myplugin
railtie.rb  version.rb

$ cat myplugin/lib/myplugin/railtie.rb
module Myplugin
  class Railtie < ::Rails::Railtie
  end
end

ref. http://api.rubyonrails.org/classes/Rails/Railtie.html

[rails-bot]

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