Change response code validation

* HTTParty has altered the DSL for Ruby 2.0
* Rather than `response.code.ok?`, will use `response.code == 200`

lib/helpers/uri_validator.rb

@@ -27,7 +27,7 @@ def valid_uri?(uri)
 
   def head_request_ok?(uri)
     response = HTTParty.head(uri)
-    return response.ok?
+    return response.code == 200
   rescue SocketError, Errno::ECONNREFUSED
     return false
   end