templates/facts.rb.erb: update URI.open syntax

Fixes #330.

Author: kenyon

templates/facts.rb.erb

@@ -14,7 +14,7 @@ require 'json'
 require 'open-uri'
 begin
   url = 'http://<%= @uri %>:<%= @port %><%= @contextpath %>/rest/api/2/serverInfo'
-  info = open(url, &:read)
+  info = URI.open(url).read
 rescue
   exit 0
 end