Dyndns - /nic/checkip.html doesn't seem to work about powerdns-admin

[trenb]

#63 Fixes this for me

mine:~ tren$ curl -v "http://10.21.4.1:9393/nic/checkip.html"
*   Trying 10.21.4.1...
* Connected to 10.21.4.1 (10.21.4.1) port 9393 (#0)
> GET /nic/checkip.html HTTP/1.1
> Host: 10.21.4.1:9393
> User-Agent: curl/7.48.0
> Accept: */*
>
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Content-Type: text/html; charset=utf-8
< Content-Length: 10
< Server: Werkzeug/0.11.10 Python/2.7.5
< Date: Fri, 01 Jul 2016 22:04:29 GMT
<
* Closing connection 0
10.21.4.16

[trenb]

lol, you're too fast for me! Thanks for looking into this and fixing it.

[ivanfilippov]

NP, I'll wait for @ngoduykhanh to accept the PR.