Update to Go 1.8

This includes most things except the containerd and runc builds
which I will do next time I update them.

Note that all golang:alpine images now for 1.8 are ALpine 3.5 based.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

tools/go-compile/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.7-alpine3.5
+FROM golang:1.8-alpine
 RUN apk update && apk add --no-cache build-base git
 
 RUN go get -u github.com/golang/lint/golint

tools/go-compile/Makefile

@@ -1,6 +1,6 @@
 .PHONY: tag push
 
-BASE=golang:1.7-alpine3.5
+BASE=golang:1.8-alpine
 IMAGE=go-compile
 
 default: push

tools/riddler/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.7-alpine
+FROM golang:1.8-alpine
 
 RUN \
   apk update && apk upgrade && \

tools/riddler/Makefile

@@ -1,6 +1,6 @@
 .PHONY: tag push
 
-BASE=golang:1.7-alpine
+BASE=golang:1.8-alpine
 IMAGE=riddler
 
 default: push