Fnlb/k8s grouper (#563)

* WIP: add k8s grouper

- This shares a great deal of behaviour with allGrouper. Once it's
tested, refactor that to share as much as possible

- Glide hell. Checked in the yaml and lock files but a glide i -v
will be required to bring vendor/ up-to-date. Will address once this
is ready.

* Update README. Make the watch tracking work.

(To follow: add the junk that was pulled in via the glide update.)

* Vendor updates.

* go fmt

* Use the allGrouper with a k8s-backed DBStore instead.

This is much tidier :-)

* Fix up go vet

vendor/github.com/PuerkitoBio/purell/purell.go

@@ -15,8 +15,8 @@ import (
 
 	"github.com/PuerkitoBio/urlesc"
 	"golang.org/x/net/idna"
+	"golang.org/x/text/secure/precis"
 	"golang.org/x/text/unicode/norm"
-	"golang.org/x/text/width"
 )
 
 // A set of normalization flags determines how a URL will
@@ -150,26 +150,22 @@ func MustNormalizeURLString(u string, f NormalizationFlags) string {
 // NormalizeURLString returns the normalized string, or an error if it can't be parsed into an URL object.
 // It takes an URL string as input, as well as the normalization flags.
 func NormalizeURLString(u string, f NormalizationFlags) (string, error) {
-	parsed, err := url.Parse(u)
-	if err != nil {
-		return "", err
+	if parsed, e := url.Parse(u); e != nil {
+		return "", e
+	} else {
+		options := make([]precis.Option, 1, 3)
+		options[0] = precis.IgnoreCase
+		if f&FlagLowercaseHost == FlagLowercaseHost {
+			options = append(options, precis.FoldCase())
+		}
+		options = append(options, precis.Norm(norm.NFC))
+		profile := precis.NewFreeform(options...)
+		if parsed.Host, e = idna.ToASCII(profile.NewTransformer().String(parsed.Host)); e != nil {
+			return "", e
+		}
+		return NormalizeURL(parsed, f), nil
 	}
-
-	if f&FlagLowercaseHost == FlagLowercaseHost {
-		parsed.Host = strings.ToLower(parsed.Host)
-	}
-
-	// The idna package doesn't fully conform to RFC 5895
-	// (https://tools.ietf.org/html/rfc5895), so we do it here.
-	// Taken from Go 1.8 cycle source, courtesy of bradfitz.
-	// TODO: Remove when (if?) idna package conforms to RFC 5895.
-	parsed.Host = width.Fold.String(parsed.Host)
-	parsed.Host = norm.NFC.String(parsed.Host)
-	if parsed.Host, err = idna.ToASCII(parsed.Host); err != nil {
-		return "", err
-	}
-
-	return NormalizeURL(parsed, f), nil
+	panic("Unreachable code.")
 }
 
 // NormalizeURL returns the normalized string.