Fix html_import_tag helper in Rails 3
Fix html_import_tag helper in Rails 3

nanowang/polymer-rails,nanowang/polymer-rails,slek120/polymer-rails,lxbrito/polymer-rails,steventill/polymer-rails,alchaplinsky/polymer-rails,IvanOM/polymer-rails,alchapone/polymer-rails,nanowang/polymer-rails,alchapone/polymer-rails,steventill/polymer-rails,quarkstudio/polymer-rails,quarkstudio/polymer-rails,IvanOM/polymer-rails,slek120/polymer-rails,alchaplinsky/polymer-rails,saratovsource/polymer-rails,steventill/polymer-rails,slek120/polymer-rails,alchapone/polymer-rails,alchaplinsky/polymer-rails,saratovsource/polymer-rails,lxbrito/polymer-rails