ruby1.9.2, rails3.0.3 google map
升级到ruby 1.9.2 rails 3.0.3时常见问题：
A:DEPRECATION WARNING: ActionController::Base.relative_url_root is ineffective. Please stop using it.
B:DEPRECATION WARNING: RAILS_ROOT is deprecated. Please use ::Rails.root.to_s.
C:can't convert Ym4r::GmPlugin::Variable to String (Ym4r::GmPlugin::Variable#to_str gives? Ym4r::GmPlugin::Variable)
解决办法：
