nokogiriの履歴
libxml2 と libxsltとlibiconvが必要
gem install nokogiri -- --with-xml2-include=/usr/local/Cellar/libxml2/2.9.3/include/libxml2 --with-xml2-lib=/usr/local/Cellar/libxml2/2.9.3/lib --with-xslt-dir=/usr/local/Cellar/libxslt/1.1.28 --with-iconv-include=/usr/local/Cellar/libiconv/1.13.1/include --with-iconv-lib=/usr/local/Cellar/libiconv/1.13.1/lib
