adds golang 1.11.x and tip to build

Signed-off-by: Mike Brown <brownwm@us.ibm.com>

.travis.yml

@@ -2,6 +2,13 @@ git:
   depth: 150
 
 language: go
+go:
+  - 1.11.x
+  - tip
+
+matrix:
+  allow_failures:
+    - go: tip
 
 sudo: required
 
@@ -26,16 +33,10 @@ install:
 before_script:
   - export PATH=$HOME/gopath/bin:$PATH
 
-jobs:
-  include:
-    - stage: Build
 script:
   - make install.tools
   - make .gitvalidation
   - make binaries
-      go: "1.10.x"
-    - stage: Test
-      script:
   - make install.deps
   - make containerd
   - sudo PATH=$PATH GOPATH=$GOPATH make install-containerd
@@ -46,4 +47,3 @@ jobs:
   # Abuse travis to preserve the log.
   - cat /tmp/test-integration/containerd.log
   - cat /tmp/test-cri/containerd.log
-      go: "1.10.x"