ruby报错信息如下：
sinber$ rake db:migrate --trace
/Users/sinber/.rvm/gems/ruby-1.9.3-p327/gems/activesupport-3.2.9/lib/active_support/dependencies.rb:251:in `block in require': iconv will be deprecated in the future, use String#encode instead.
这是由于没有设置字符编码报的错
解决办法：
终端输入命令
sinber$ export RUBYOPT="-KU -E utf-8:utf-8"