tpl: Add WebP images support

Fixes #3529

Author: bep

tpl/images/images.go

@@ -23,6 +23,8 @@ import (
 	_ "image/jpeg"
 	_ "image/png"
 
+	_ "golang.org/x/image/webp"
+
 	"github.com/gohugoio/hugo/deps"
 	"github.com/spf13/cast"
 )

vendor/vendor.json

@@ -364,6 +364,12 @@
 			"revision": "850760c427c516be930bc91280636328f1a62286",
 			"revisionTime": "2017-06-13T19:24:08Z"
 		},
+		{
+			"checksumSHA1": "wwirbKM4d69iWA4s9JwpXTsda3A=",
+			"path": "golang.org/x/image/webp",
+			"revision": "426cfd8eeb6e08ab1932954e09e3c2cb2bc6e36d",
+			"revisionTime": "2017-05-14T06:33:48Z"
+		},
 		{
 			"checksumSHA1": "VrzPJyWI6disCgYuVEQzkjqUsJk=",
 			"path": "golang.org/x/net/idna",