Fix request_details in isBogon case

The hash 'details' is assigned to before creation, leading to
```
undefined method `[]=' for #<IPinfo::Response:0x...>
```

Author: mikecarlton

lib/ipinfo.rb

@@ -119,6 +119,7 @@ def prepare_http_client(httpc = nil)
 
     def request_details(ip_address = nil, host_type)
         if isBogon(ip_address)
+            details = {}
             details[:ip] = ip_address
             details[:bogon] = true
             details[:ip_address] = IPAddr.new(ip_address)