url_handlers: tools: Make the DNS domain export form use a GET

Change the DNS domain extraction form method from a POST to a GET. I
think this is more correct as we aren't changing anything with this
query, simply retrieving data.

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>
url_handlers: tools: Remove the CSRF token

There is no need to CSRF protect the domain extraction. This causes no
changes to happen server side, only to download DNS data.

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>
templates: tools: Rename 'Extract' to 'Export'

I think this reads better.

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>
url_handlers: tools: Handle missing options better

If the user didn't select a domain and or format they would get a 502
Bad Gateway page due to the client not being sent any proper HTTP
response from the application.

Handle this case by sending a Location header for /tools/

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>