Update travis CI to support go1.11

.travis.yml

@@ -4,12 +4,15 @@ sudo: required
 services:
   - docker
 
-go:
-  - tip
-  - 1.9
-install:
-  - go get -d -v ./...
-  - go build
+matrix:
+  include:
+  - go: "1.10.x"
+    script:  go test -v ./...
+  - go: "1.11.x"
+    script: go test -v -mod=vendor ./...
+env:
+  - GO111MODULE=on
+install: true
 script:
   - go get github.com/axw/gocov/gocov
   - go get github.com/mattn/goveralls
@@ -22,6 +25,3 @@ before_install:
   - sudo pip install codecov
 after_success:
   codecov
-notifications:
-  email:
-    - [email protected]