rename nginx[:install_path] attribute to nginx[:source][:prefix]
rename nginx[:install_path] attribute to nginx[:source][:prefix]

Signed-off-by: jtimberman <d6955d9721560531274cb8f50ff595a9bd39d66f@opscode.com>

myplaceonline/nginx,Sauraus/chef_nginx,Roblox/chef_nginx,spulec/nginx_private,periscopedevelopment/nginx,7bfa689ac3c4be50f8ba6c1ea8c5f316/nginx,kri5/nginx,AudaxHealthInc/nginx,fsultan/nginx,Altiscale/nginx,cpbtechnology/nginx,auth0/chef-nginx,periscopedevelopment/nginx,evertrue/nginx-cookbook,axos88/chef_nginx,jharveysmith/nginx,periscopedevelopment/nginx,cookbooks/nd-chef-opscode-nginx,seefood/tengine-cookbook,blmlove409/nginx_cookbook,8la/nginx,gansbrest/nginx,Sauraus/chef_nginx,zuazo-forks/opscode-cookbooks-nginx,kri5/nginx,7bfa689ac3c4be50f8ba6c1ea8c5f316/nginx,birarda/nginx,channelgrabber/nginx,fsultan/nginx,feedhenry-cookbooks/nginx,birarda/nginx,ttab/nginx,8la/nginx,whatcould/nginx,fsultan/nginx,cpbtechnology/nginx,Roblox/chef_nginx,miketheman/nginx,cookbooks/oc-nginx,myplaceonline/nginx,Altiscale/nginx,birarda/nginx,channelgrabber/nginx,auth0/chef-nginx,whatcould/nginx,cookbooks/hw-nginx,channelgrabber/nginx,AudaxHealthInc/nginx,Roblox/chef_nginx,8la/nginx,Lispython/nginx-cookbook,cookbooks/mc-nginx,ffuenf/nginx,evertrue/nginx-cookbook,gansbrest/nginx,ttab/nginx,7bfa689ac3c4be50f8ba6c1ea8c5f316/nginx,cokeboL/nginx,miketheman/nginx,cokeboL/nginx,AudaxHealthInc/nginx,blmlove409/nginx_cookbook,chef-cookbooks/chef_nginx,luishdez/nginx-cookbook,newlywish/nginx,miketheman/nginx,luishdez/nginx-cookbook,chef-cookbooks/chef_nginx,zuazo-forks/opscode-cookbooks-nginx,Sauraus/chef_nginx,evertrue/nginx-cookbook,cpbtechnology/nginx,chef-cookbooks/chef_nginx,ffuenf/nginx,luishdez/nginx-cookbook,jharveysmith/nginx,gansbrest/nginx,kri5/nginx,feedhenry-cookbooks/nginx,ffuenf/nginx,ttab/nginx,newlywish/nginx,trotttrotttrott/cookbook-nginx_node-tail,Altiscale/nginx,axos88/chef_nginx,sanguis/nginx,cokeboL/nginx,newlywish/nginx,blmlove409/nginx_cookbook,axos88/chef_nginx