This is the sample application for Ruby on Rails Tutorial: Learn Rails by Example by Michael Hartl.
Installing nokogiri:
gem install nokogiri -- --with-xslt-lib=/usr/local/Cellar/libxslt/1.1.26/lib --with-xslt-include=/usr/local/Cellar/libxslt/1.1.26/include/libxslt --with-iconv-dir=/usr/local/Cellar/libiconv/1.14 --with-xml2-lib=/usr/local/Cellar/libxml2/2.7.8/lib --with-xml2-include=/usr/local/Cellar/libxml2/2.7.8/include/libxml2