Fix gogenerate travis check

.travis.gogenerate.sh

@@ -1,6 +1,11 @@
 #!/bin/bash
 
-go generate
+if [[ "$TRAVIS_GO_VERSION" =~ ^1\.[45](\..*)?$ ]]; then
+  exit 0
+fi
+
+go get github.com/ernesto-jimenez/gogen/imports
+go generate ./...
 if [ -n "$(git diff)" ]; then
   echo "Go generate had not been run"
   git diff

.travis.yml

@@ -7,6 +7,7 @@ go:
   - 1.5
   - 1.6
   - 1.7
+  - 1.8
   - tip
 
 script: