Upstream resolver should be configurable

[hughsaunders]

Currently the external resolver is hard coded to 8.8.8.8 (Google public DNS).
https://github.com/fifthsegment/Gatesentry/blob/master/application/dns/server/server.go#L27

Two use cases for this being configurable:

1. I have a local DNS resolver that I use to access local resources. Gate sentry must forward requests through this resolver or my local resources become inaccessble.
2. Some users may be unwilling to hand over all their DNS queries to Google.

[fifthsegment]

Great suggestion. Would you be interested in creating a PR for this?

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[fifthsegment]

#110

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.