While looking into the proxy middleware it appears that there are
several golint messages:
```
ubuntu@ubuntu:~/coredns$ golint middleware/proxy/
middleware/proxy/lookup.go:66:1: exported method Proxy.Forward should have comment or be unexported
middleware/proxy/proxy.go:24:6: exported type Client should have comment or be unexported
middleware/proxy/proxy.go:107:1: exported function Clients should have comment or be unexported
middleware/proxy/reverseproxy.go:10:6: exported type ReverseProxy should have comment or be unexported
middleware/proxy/reverseproxy.go:16:1: exported method ReverseProxy.ServeDNS should have comment or be unexported
middleware/proxy/upstream.go:42:6: exported type Options should have comment or be unexported
```
This fix addressed the above golint messages.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Move all (almost all) Go files in middleware into their
own packages. This makes for better naming and discoverability.
Lot of changes elsewhere to make this change.
The middleware.State was renamed to request.Request which is better,
but still does not cover all use-cases. It was also moved out middleware
because it is used by `dnsserver` as well.
A pkg/dnsutil packages was added for shared, handy, dns util functions.
All normalize functions are now put in normalize.go