Makefile: use Go 1.10.2

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

Makefile

@@ -47,7 +47,7 @@ docker-remove:
 
 
 
-GO_VERSION ?= 1.10.1
+GO_VERSION ?= 1.10.2
 ETCD_VERSION ?= $(shell git rev-parse --short HEAD || echo "GitNotFound")
 
 TEST_SUFFIX = $(shell date +%s | base64 | head -c 15)
@@ -62,16 +62,16 @@ endif
 
 # Example:
 #   GO_VERSION=1.8.7 make build-docker-test
-#   GO_VERSION=1.9.5 make build-docker-test
+#   GO_VERSION=1.9.6 make build-docker-test
 #   make build-docker-test
 #
 #   gcloud docker -- login -u _json_key -p "$(cat /etc/gcp-key-etcd-development.json)" https://gcr.io
 #   GO_VERSION=1.8.7 make push-docker-test
-#   GO_VERSION=1.9.5 make push-docker-test
+#   GO_VERSION=1.9.6 make push-docker-test
 #   make push-docker-test
 #
 #   gsutil -m acl ch -u allUsers:R -r gs://artifacts.etcd-development.appspot.com
-#   GO_VERSION=1.9.5 make pull-docker-test
+#   GO_VERSION=1.9.6 make pull-docker-test
 #   make pull-docker-test
 
 build-docker-test: