Merge branch 'release-1.7'

.travis.yml

@@ -3,7 +3,7 @@ sudo: false
 language: go
 
 go:
-- 1.8.x
+- 1.9.x
 - 1.x
 
 go_import_path: github.com/prometheus/prometheus

circle.yml

@@ -2,7 +2,7 @@ machine:
   environment:
     DOCKER_IMAGE_NAME: prom/prometheus
     QUAY_IMAGE_NAME: quay.io/prometheus/prometheus
-    DOCKER_TEST_IMAGE_NAME: quay.io/prometheus/golang-builder:1.8-base
+    DOCKER_TEST_IMAGE_NAME: quay.io/prometheus/golang-builder:1.9-base
     REPO_PATH: github.com/prometheus/prometheus
   pre:
     - sudo curl -L -o /usr/bin/docker 'https://s3-external-1.amazonaws.com/circle-downloads/docker-1.9.1-circleci'