Feature Request: Make API Url Configurable

[lvfrazao]

Currently it appears that the NS1 API URL is hardcoded to https://api.nson.net/v1

ns1-app/src/plugin.json

Line 11 in 4a2e2d4

"url": "https://api.nsone.net/v1",

Some NS1 customers are running the Private version of NS1's DNS software and would like to be able to use the Grafana NS1 app to monitor those DNS instances. It would be possible to do so if the API host was a configurable option.