Adding fixes for arista chef clients

 - checked old sites (iad1,dpa1), nagios doesn't pull arista chef clients
 - updated recipes/server.rb to poll chef for aristas
 - updated templates/hosts.cfg.erb to generate host block
Changed search(:node, role: ... to roles:
Merge pull request #10 from syspimp/fixing-aristas

Adding fixes for arista chef clients