Remove Ubuntu 10.04 support
Remove Ubuntu 10.04 support

This simplifies the attributes setup and 10.04 is now EoL
chef-cookbooks/squid,kevinrbabcock/squid,bitmonk/chef-squid,opscode-cookbooks/squid,criteo-forks/squid,PrecisionNutrition/squid,opscode-cookbooks/squid,jpmat296/squid,chef-cookbooks/squid,snkutlu/squid,akaasjager/squid-icap,PrecisionNutrition/squid,criteo-forks/squid,kevinrbabcock/squid,snkutlu/squid,jpmat296/squid,akaasjager/squid-icap,bitmonk/chef-squid