test and build with golang 1.11 (#4637)

linters were failing with: pkg/urlutil/urlutil_test.go:1::warning: file is not gofmted with -s (gofmt)
Signed-off-by: Helgi Þorbjörnsson <helgith@gmail.com>

.circleci/config.yml

@@ -4,7 +4,7 @@ jobs:
     working_directory: /go/src/k8s.io/helm
     parallelism: 3
     docker:
-      - image: golang:1.10
+      - image: golang:1.11
     environment:
       PROJECT_NAME: "kubernetes-helm"
     steps:

Makefile

 DOCKER_REGISTRY   ?= gcr.io
 IMAGE_PREFIX      ?= kubernetes-helm
-DEV_IMAGE         ?= golang:1.10
+DEV_IMAGE         ?= golang:1.11
 SHORT_NAME        ?= tiller
 SHORT_NAME_RUDDER ?= rudder
 TARGETS           ?= darwin/amd64 linux/amd64 linux/386 linux/arm linux/arm64 linux/ppc64le linux/s390x windows/amd64