Cleanup: put middleware helper functions in pkgs (#245)

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

middleware/errors/errors.go

@@ -9,6 +9,8 @@ import (
 	"time"
 
 	"github.com/miekg/coredns/middleware"
+	"github.com/miekg/coredns/middleware/pkg/roller"
+	"github.com/miekg/coredns/request"
 
 	"github.com/miekg/dns"
 	"golang.org/x/net/context"
@@ -19,7 +21,7 @@ type ErrorHandler struct {
 	Next      middleware.Handler
 	LogFile   string
 	Log       *log.Logger
-	LogRoller *middleware.LogRoller
+	LogRoller *roller.LogRoller
 	Debug     bool // if true, errors are written out to client rather than to a log
 }
 
@@ -29,7 +31,7 @@ func (h ErrorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns
 	rcode, err := h.Next.ServeDNS(ctx, w, r)
 
 	if err != nil {
-		state := middleware.State{W: w, Req: r}
+		state := request.Request{W: w, Req: r}
 		errMsg := fmt.Sprintf("%s [ERROR %d %s %s] %v", time.Now().Format(timeFormat), rcode, state.Name(), state.Type(), err)
 
 		if h.Debug {
@@ -53,7 +55,7 @@ func (h ErrorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns
 		return
 	}
 
-	state := middleware.State{W: w, Req: r}
+	state := request.Request{W: w, Req: r}
 	// Obtain source of panic
 	// From: https://gist.github.com/swdunlop/9629168
 	var name, file string // function name, file name