Issue indexer queue redis support (#6218)

* add redis queue

* finished indexer redis queue

* add redis vendor

* fix vet

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* switch to go mod

* Update required changes for new logging func signatures

vendor/github.com/go-redis/redis/.travis.yml

@@ -0,0 +1,19 @@
+sudo: false
+language: go
+
+services:
+  - redis-server
+
+go:
+  - 1.9.x
+  - 1.10.x
+  - 1.11.x
+  - tip
+
+matrix:
+  allow_failures:
+    - go: tip
+
+install:
+  - go get github.com/onsi/ginkgo
+  - go get github.com/onsi/gomega