Accept HTTP checks for monit_procmon

Allows for passing HTTP checks to monit_procmon which are then
added to the Monit configuration file for that process. e.g.:

monit_procmon "keystone" do
  procname platform_options["keystone_service"]
  sname platform_options["keystone_process_name"]
  process_name sname
  script_name procname
  http_check [
    {
      :host => "localhost",
      :port => 5000
    },
    {
      :host => "localhost",
      :port => 35357
    }
  ]
end