Update to go v1.11.6 (security updates). (#77)

diff --git a/.travis.yml b/.travis.yml
index a5928fd..7938e89 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,7 @@
 sudo: required
 language: go
 go:
-  - "1.11.5"
+  - "1.11.6"
 services:
   - docker
 notifications:
diff --git a/build.gradle b/build.gradle
index 149426f..c4d7384 100644
--- a/build.gradle
+++ b/build.gradle
@@ -43,7 +43,7 @@
 
 golang {
   packagePath = 'github.com/apache/incubator-openwhisk-runtime-go'
-  goVersion = '1.11.5'
+  goVersion = '1.11.6'
 }
 
 build.dependsOn vendor
diff --git a/golang1.11/CHANGELOG.md b/golang1.11/CHANGELOG.md
index 18f48d7..68f6262 100644
--- a/golang1.11/CHANGELOG.md
+++ b/golang1.11/CHANGELOG.md
@@ -21,4 +21,4 @@
 
 ## Apache 1.13.0-incubating (next release)
 - Initial version
-- Go 1.11.5
+- Go 1.11.6
diff --git a/golang1.11/Dockerfile b/golang1.11/Dockerfile
index 6b68c38..f1cfbd7 100644
--- a/golang1.11/Dockerfile
+++ b/golang1.11/Dockerfile
@@ -1,4 +1,4 @@
-FROM golang:1.11.4
+FROM golang:1.11.6
 RUN echo "deb http://deb.debian.org/debian stretch-backports main contrib non-free" \
      >>/etc/apt/sources.list &&\
     apt-get update && apt-get install -y \